- A look at problematic Toyota advertising and the tricky world of reducing environmental impact of transport

Self Charging Hybrid: Dissecting a Juicy Case of Advertising Hype & A Bit More

1d ago


In this piece, I take a look at problematic Toyota advertising, explain the underlying technology and delve in to the tricky world of reducing environmental impact of transport.

Long Story Short

• Since 2017-18, Toyota and its premium brand Lexus has been using the term "Self Charging" when advertising their latest cars with hybridised gasoline-electric propulsion units. Ford and Hyundai/Kia has followed Toyota in doing the same

• A closer look at the technology reveal the term "Self Charging Hybrid" to be a misnomer which could create consumer confusion on subjects broader than cars

• The insistent use of the "Self Charging" misnomer in Toyota advertising is unworthy & unbecoming of Toyota's engineering prowess & heritage

• This matters because, as engineers we are working hard to help reduce impact of transport on the environment without crashing the economy; The last thing we need is a confused and misinformed consumer with compromised ability to take appropriate decisions

• As a daily user of a pure electric car, part of me think hybrid cars are a waste-of-time technology invented to buy time for the combustion engine & oil industry

• However a technology agnostic look at the fundamentals of saving the environment, reveal a more complex story. Especially when we break out of our bubbles & think solutions relevant for different parts of the world

• Our challenges are such that, hybrid cars remain as an important tool alongside pure electric vehicles. Especially in a situation where we need to urgently reduce environmental burden of transport

• It is extremely important to discuss these complex matters with the public while maintaining clarity of information. This is not helped by advertising hype that muddy the waters

Be Warned

In this article I go full "James May" on this subject. So be warned; this is quite a long article.

If you are really curious, got the gumption and sufficiently caffeinated, you may continue.

If not, you may skim straight down to Section 5 & Conclusions.

Why am I writing this on Drivetribe?

I love cars as much as any one on Drivetribe. However I don't want that love to destroy the beautiful world I want to drive in. I also don't want that love to enslave our future generations to the OPEC.

The best way to solve this dilemma is to get clued-up about the big problems and try to take the problem solving off the hands of the clueless.


I learned to drive in a Toyota. My previous car was a Toyota. As a project car, I keep a 1998 Lexus with a V8 engine. As an engineer I admire Toyota's engineering prowess, but I take issue with their latest advertising slogan "Self Charging Hybrid".

In a previous article I shared how plug-in charging can make or break the electric car user experience.  This time, I look at Toyota's advertising claim that their hybrid vehicles “ Self Charge ” with no need to plug-in.

This advertising slogan "Self Charging Hybrid" does not make any sense. I could not resist going full "James May" on this matter to investigate the rationale behind this slogan. This article is a look at the technology and why I think it's irresponsible to use advertising slogans like this.

Then I take this inquiry further to understand the point of hybrids and the role they play alongside battery electric vehicles (BEV) in reducing the environmental impact of transport. And in the end I list (with correct terminology) the 5 main powertrain types that will propel cars around the world.

If you're not a person of science or have forgotten what the energy related units mean, please scroll down to the bottom of this article for simplified explanations.

1. What is so special about Toyota hybrids

1.1 A Brief History of Electrified Toyota Cars

Quoted sales are cumulative values

Toyota originally used “Hybrid Synergy Drive” or HSD to tag vehicles that combine a gasoline engine, electric motors & battery pack operating synergistically to deliver efficient propulsion.

Under the bonnet/hood of the 2010 Toyota Prius I briefly owned before switching to a fully electric car

Around the release of Prius Mk 4 around 2016, Toyota advertising started to brand their cars fitted with hybrid powertrain as “Self Charging Hybrids”. Toyota advertising adopted a tone that present Self Charging Hybrid as a product superior to electric vehicles; as there is no need to plug-in to external electric power source to charge the battery pack.

Hyundai/Kia and Ford advertising has followed suit to also use the term “Self Charging” to advertise their hybrid electric vehicles.

However, the use of the term “Self Charging” as a qualifier for hybrid vehicles appear to be strangely absent or at least difficult to find in their advertising in the United States.

1.2 The Reputation

Toyota is a pioneer in combining (hybridising) electric power with conventional gasoline combustion to produce robust and fuel efficient powertrains for affordable passenger cars. A cursory look at the high-mileage used car advertisements or conversations with taxi drivers provide an interesting view of how this reputation has developed.

Each point in the above graph represents an advertisement in the UK of a used vehicle between the age of 3 and 15 years with mileages between 160,000 km (100,000 miles) and 450,000 km (278,000 miles). To provide some context, the graph also presents data for one of the most popular cars in Europe (Volkswagen Golf) with gasoline engine specifications providing approximately equivalent performance to that of a Toyota Prius.

There are several factors that combine to create what we can read in the above data. The key factor is the longevity of gasoline cars with Toyota hybrid system. In the UK, you can buy factory-fresh gasoline cars of a size similar to a Toyota Prius for ~ £10,000. Despite this, even high mileage Toyota hybrids are sought after due to their durability & efficiency.

2. The Fundamentals of Going from A to B

To understand the reason for the existence of hybrid cars, we have to look at the way energy is used to move a vehicle.

In a conventional vehicle with only an internal combustion engine (IC engine) the stored energy in the gasoline tank will take the following approximate paths in the process of propelling you from point A to point B.

Kinetic energy is the type of energy stored in the mass of a vehicle in the form of movement in relation to the ground. This is the useful type of energy that takes you from A to B.

As of 2019, gasoline engines are capable of converting up to 25% to 40% of the stored energy into kinetic energy to propel the car, occupants & cargo. A smaller proportion is spent to operate auxiliary systems (e.g. air conditioning) and the rest of the energy is wasted as unusable thermal energy through coolant and tail-pipe exhaust gasses. The proportion of useful energy we can extract from combustion can change by factors such as speed, terrain, weight and weather.

There are many ways of reducing waste to ultimately reduce the total energy budget to move a car. Techniques of reducing this waste boil down to the following

1. Operate IC engine at its sweet-spot that provide best thermal efficiency

2. Eliminate idling and low efficiency IC Engine operating points

3. Recover waste energy for re-use

4. Finer management of auxiliary loads (Air-con, heating, pumps, electrics, etc) and use recovered waste energy to drive auxiliaries

Implementing these 4 strategies by combining IC Engine with one or more electric motors, augment the energy flow of a vehicle to something similar to the following.

Hybrid car energy flow

Electric motors convert electrical energy stored in a battery in to kinetic energy. However, unlike IC engines, electric motors can also generate electricity by resisting rotation of wheels (non-friction/regenerative braking) to absorb kinetic energy of the vehicle. Hence these electric machines are referred to as motor-generators (MG).

The battery pack required to power the MG is sized just enough to either

• Store electricity that originated only from the IC engine (i.e. IC engine directly driving the MG or regenerative braking) - 0.5 to 2 kWh battery capacity

• Store electricity that originated from the IC engine and from an external energy source (e.g. plug-in to electricity grid) - 8 to 20 kWh battery capacity

Plug-in Hybrid car energy flow. Battery size limited to make sure IC engine doesn't become too much of a dead weight across the lifetime mileage of the car

Manufacturers decide the capabilities and the physical layout of the hybrid system by carefully balancing costs and benefits. To apply this improvement, a hybrid system bring together

• Multiple propulsion units (IC engine & one or more MGs)

• Two braking methods (friction & electro-regenerative)

• Multiple stored energy forms (Liquid or gaseous combustible and electricity)

• Multiple temperature control units (IC engine, MGs, power electronics, battery, cabin)

• Auxiliaries decoupled from IC engine (electrically driven compressors & pumps, etc.)

Stitching this matrix of fundamentally different elements together into one seamless powertrain is an exceptionally complex engineering challenge.

Creating such a system as something robust, affordable & appropriate for mass production require considerable technical and commercial ingenuity. Toyota’s achievement of taking this to market first & delivering over 10 million units globally is something very special.

3. How Toyota Advertising Muddy the Waters with Self-Charging

In the English language a qualifier is a word/term used to modify, frame or emphasise the meaning of another word. For example

• High Voltage Hybrid - “high voltage” is a qualifier of the word “hybrid”

• Self Charging Hybrid - “Self Charging” is a qualifier of the word “hybrid”

Extreme care is required when using qualifiers to emphasise meaning or distinguish an item within a related group (especially in science, engineering & public information). The rules-of-thumb/guidance for qualifiers are

1. The qualifier is not superfluous

2. The qualifier points to a unique/distinguishing property

3. The qualifier by-it-self (when not used as a qualifier), is benign in meaning or not refer to a falsehood

Ignoring this guidance for using qualifiers is not always catastrophic. However, it could lead to counterproductive results such as confusion, suspicion and mistrust.

When the term "Self-Charging" is used as a qualifier for hybrid vehicles, it breaks all 3 of the above rules. Let's look at how it essentially muddy the waters.

Issue 1:

“Self Charging” by itself is a volatile term that always wait precariously to be pacified by an explanation.

Babies are an example of volatile entity that require near constant tending to.

Batteries cannot self charge the same way rivers cannot flow up stream unless an external force is acted upon. I'm certain Toyota advertisers are not implying that batteries can self charge in such magical means.

However, it is highly presumptuous to think that all members of the public know this fundamental fact. We can’t control what people imply or deduce based on their own level of education or intuition. It’s highly irresponsible to use terms that even unintentionally risk leading the general public to reach grossly inaccurate conclusions.

Issue 2:

A key published reason for using the “Self Charging” term is not a unique distinguishing property of hybrid vehicles.

Could the pretend Wallys please sit down.

Advertising by manufacturers (Toyota, Ford & Hyundai/Kia) and some motoring journalists explain that “Self Charging” is referring to how a hybrid systems use regenerative braking to recharge the battery to remove the need to plug-in to external power sources.

All types of hybrid systems and pure electric cars possess regenerative braking capability. It is not a property unique to hybrid cars like the Toyota Prius or a Hyundai ioniq.

Issue 3:

It is unnecessary.

Due to Toyota’s pioneering work & popularity, Toyota practically own the term “hybrid” in the minds of consumers. The technology has not fundamentally changed. There is no desperate need for a qualifier.

Insistent use of this term is akin to republishing a book on human anatomy to re-label the “heart” as the “Self Beating Heart”.

Thought experiment: Results of republishing a book on human anatomy to re-label the “heart” as the “Self Beating Heart” for no particular reason

These three issues together in effect make the term “Self Charging Hybrid” a misnomer. If advertisers think it is imperative to add a qualifier, then it should be done correctly. If not, the public may even be led to suspect less innocent intentions for its insistent use.

4. Global Fossil Fuelled Distances - Reducing environmental impact of transport

One of the biggest issues we are trying to solve without crashing economies & plunging people into poverty is the environmental impact of transport. The transport sector burns large amounts of oil for energy and as a consequence, emits CO2 and other greenhouse gases that lead to global warming. If you are not aware of the greenhouse effect that cause global warming, this Youtube link explains the fundamentals.

Even if you don't believe or understand the climate argument, it still makes good economic and geo-political sense to curb reliance on oil for transport. The following summaries from the International Council on Clean Transport (ICCT) explain the scale of this challenge at hand.

MBD = Million Barrels per Day; A barrel is about 159 litres

When thinking of solutions to the above problem, the maverick in me thinks hybrids are a waste of time & a compromise to simply extend the relevance of industrial behemoths that are the IC engine and the petrochemical industry. Just switch to Battery Electric Vehicles (BEV) and the new world will adjust the same way it adjusted away from horses.

Unfortunately the pragmatist in me sees the reality as something more complex. We are not living in the 1920s. Human population is much larger. We have large & complex transport networks our economies depend on. Our problems are big and the solutions they demand are equivalent in scale, complexity & urgency.

Just looking at BEV sales is inadequate to figure out ways to urgently solve environmental damage from transport. A more sensible technology agnostic approach is to look at it from the perspectives of

1. Cumulative vehicle fleet kilometres driven using fossil fuels (fossil fuelled distances)

2. Environmental impact of the whole life cycle of a vehicle (from manufacture to disposal) but this is a subject too complicated to address in this article.

To make any progress in reducing environmental damage from transport, we have to reduce fossil fuelled distances using the following routes

• Reduce global vehicle distances driven by investing in better public transport (however it is highly unlikely to get people to travel less or overcome their preference for personal transport)

• Reduce energy required to drive each km

• Transition to cleaner sources of energy

BEV and hybrid vehicles earn their money by reducing energy per km and enabling a shift to cleaner energy sources (i.e. reducing fossil fuelled distances). So we have solutions or options to manage the environmental impact of transport.

However, having solutions and applying solutions are two very different things when trying to get results.

We urgently need to reduce global fossil fuelled distances. With this urgency in mind, the following 3 points should be thought through when applying solutions

Point 1: Vehicle Utilisation

The environmental impact of transport is a factor of the number of vehicles & how much they are used (utilisation).

There are over 1 billion vehicles in the world. Deploying new technologies to transform this fleet takes a large amount of money, material & energy. With all the will in the world this is not something that can be fixed within 5 or 10 years. At least to make a start, governments & consumers must make appropriate decisions.

Lithium-ion battery technology is a key enabler for the BEV renaissance we’ve observed over the last 5+ years. Unfortunately it’s also one of the bottlenecks. In a very optimistic scenario by 2030, we may be able to make enough battery packs to convert about 25% of global passenger car population to BEV (I’m referring to number of vehicles on the road; not sales figures).

If this valuable battery resource is fitted to average passenger cars that drive ~< 12,000 km per year, this will have minuscule impact on reducing fossil fuelled distances.

Ideally, batteries should be prioritised for vehicles accumulating high number of kilometres over time. Not average cars that sit idle for most of the day.

Pathway for a more balanced approach would be to spread the benefits of Lithium-ion batteries over a larger fleet of individual vehicles by

• More hybrid cars (high number of small batteries Vs small number of big batteries)

• More Hybrids and BEVs as taxis, other shared/on-demand or autonomous vehicles

• Incentivising smaller BEV over large BEV for private passenger cars

• Battery Electric trucks, buses & light commercial vehicles

Vehicle to Grid (V2G) technologies can also help BEVs to make its battery useful while sitting at home or in car parks.

Point 2. The need to think global & global numbers

The need to think globally when solving large scale environmental issues is self evident. We are predisposed to think within our own geographic & ideological bubbles. What is myopic & foolish is to call oneself an environmentalist and protest in London, to demand blanket bans of IC engines by 2025.

If we are at an urgent war footing, number of guns is as important as the size of guns. To significantly reduce global fossil fuelled distances urgently, we need to prioritise technology that we can churn out by the millions anywhere between Detroit & Chongqing.

To bring about urgent improvements we have to focus on the majority of mundane cars, trucks & buses that do the donkey-work of transport networks. Not the few glamorous luxury cars

For now, the most realistic option to achieve the numbers globally is prioritising deployment of a mix of BEV & hybrid cars with a bias on hybrids (at least for the short term) to urgently reduce energy per km driven.

It has become fashionable to envision a quick delete of the IC engine from roads around the world. If we are to save the world without pulling the rug out from underneath our own feet, we will have to bear with IC engines globally for some time beyond 2030.

Point 3. Public knowledge & engagement

Building millions of new vehicles with new technology is useless if people can’t or won’t buy them.

Can’t buy because it’s too expensive, infrastructure issues, insufficient capability, etc.

Won’t buy because of ignorance, confusion, mistrust, complexity, false information, misnomers, poor cost-benefit balance etc.

Governments & industry must engage with the public to maintain clarity and provide prudent options. Options the public can subscribe to, to reduce fossil fuelled distances without jeopardising their economic prospects. In this context, the use of advertising that persistently use misnomers are counterproductive and highly irresponsible.

5. What Will Power Road Vehicles in the 2020s

The following are the types of vehicle propulsion systems that are most likely to dominate mainstream vehicles in the next decade. These are approximate generalised specifications (not specific to a particular model) presented with appropriate qualifiers.

5.1. Conventional IC engine

Conventional to 2019 with no waste energy recovery using an add-on electric system.

Conventional IC Engine car energy flow

Thinking globally, non-hybrid IC engined cars will be with us on the roads in quite non-glamorous work vehicles beyond 2030. These are already able to manage the most harmful (non CO2) tailpipe emissions.

Some may use natural gas as a lower carbon energy source. Synthetic gas or liquid fuels made from renewable energy may offer some hope of continuity. Biggest competitive issues could be how the most advanced IC engines age and affect operating costs compared to BEV.

5.2. Low Voltage Hybrid

Hybrid car energy flow

Also referred to as Mild Hybrid. Use gasoline, diesel or gas combustion as the only energy source.

To avoid the cost of a high voltage electrical system, manufacturers are resorting to a 48 Volt electrical system to achieve a scaled down hybrid function. The capabilities of the hybrid system divide this classification in to two. Improved fuel efficiency and emissions compared to conventional IC engine but not as capable as high voltage hybrid.

Renault Scenic diesel mild hybrid

Standard Low Voltage Hybrid

• No pure electric drive

• 48 Volt battery < 0.5 kWh capacity with no plug-in charging

• Limited regenerative braking

• Essentially a belt driven 48 Volt MG replaces the traditional 12 Volt alternator

Advanced Low Voltage Hybrid

• Limited pure electric drive (at low speeds to creep in traffic or do parking maneuvers with IC engine off)

• 48 Volt battery of 0.4 to 1 kWh capacity with no plug-in charging

• Limited regenerative braking

• 48 Volt MG located in transmission

• Electrically driven auxiliaries

5.3. Non-plug-in High Voltage Hybrid

Gasoline or diesel combustion as the only energy source. Energy stored in the battery originate from this fuel stored in the tank. Energy storage replenished by filling the tank with fuel, same as a conventional car.

Hybrid car energy flow

• Pure electric drive below 50 km/h for less than 5 km

• 100 to 400 Volt electrical system

• 0.5 to 2 kWh battery with no plug-in capability

• One or more MGs

• Regenerative braking

• Electrically driven auxiliaries

2016 Toyota Prius

5.4. Plug-in High Voltage Hybrid

Gasoline, diesel or gas combustion as the primary energy source.

PHEV energy flow

Ability to plug-in to utility electricity grid as a secondary energy source.

• Pure electric drive below 120 km/h for less than ~60 km

• 100 to 400 Volt electrical system

• 8 to 20 kWh battery with plug-in charging capability

• One or more MGs

• Regenerative braking

• Electrically driven auxiliaries

Toyota Prius plug-in hybrid or Prius PHEV

These are specifically designed to enable only a short routine journey / commute on electric energy stored. Due to battery sized just enough for the intended purpose, maximum charging power is limited (less than 20 kW) as the expectation is to charge slow at home or at the work place.

However, owners on longer journeys resort to using the scarce public rapid BEV charging points. The vehicles only draw 20 kW or less from rapid chargers capable of delivering 50 or 100+ kW.

Disliked by some public charging station operators as they get to sell less energy per charging session & they are likely to stop plug-in hybrids from using their rapid chargers. Hated by BEV owners as these vehicles occupy limited rapid charge points and delay their journeys.

A motorway rapid charger being occupied by a Mitsubishi PHEV, may be not for long.

5.5. Battery Electric Vehicle (BEV)

Plug-in to utility electricity grid as the only energy source.

BEV energy flow

• 300 to 800 Volt electrical system

• 50 kWh battery or larger & fitted with capability to add more than 400 km of driving range per hour of charging using rapid charger

• Regenerative braking

• One or more MGs

• Electrically driven auxiliaries


Toyota Self Charging Hybrids are just gasoline vehicles. Arguably the most efficient gasoline vehicles you can buy; but still gasoline vehicles. Persistence with the term "Self charging" in advertising by Toyota, Ford and Hyundai/Kia is highly irresponsible in a situation where we need to engage with consumers to solve some complex problems.

A reliable and efficient transport network is the life blood of a thriving country. It's a key enabler of social mobility from the figurative and literal sense. Is it right to base something so important on an energy supply dominated by governments you wouldn't trust with a life of a chicken, let alone the future of your kids?

An analogy of the OPEC blighting the lives of your kids. This could also be IT giants but thats a whole different story

Ignore the environment. It makes perfect economic and geo-political sense to reduce the fossil fuel reliance of our transport networks.

Even though I'm an engineer & a daily user of a BEV, I struggle to see how BEVs by themselves are going to help us to urgently reduce fossil fuel use in transport around the world. (e.g. put a BEV in India today or even 5 or 10 years time, majority of its driving will most probably be powered by coal based electricity)

Ideal ways to reduce fossil fuelled distances involve developing renewable energy, energy storage, public transport, on-demand mobility, autonomous vehicles, etc. Developing & then deploying these around the world is likely to take more than one decade.

I think the current predicament of humanity is similar to the situation faced by the 1970 Apollo 13 moon mission crew. We have limited time and resources to deal with a complex life threatening problem. When the Apollo 13 crew had to urgently make a square CO2 scrubber cartridge fit a round receiver of a spare life support system, they had 2 options

1. Die of suffocation in a failing space ship

2. Harvest all the limited, non ideal options they have within the ship to urgently jury-rig the square cartridge to work with the round hole without breaking the system

As a BEV driver I wish all cars, buses & trucks were powered by locally sourced renewable energy. This may be possible but not in the timescales some journalists, analysts and media personalities may claim.

We need to communicate and get the public to think through these complexities as much as possible. Using misnomers (e.g. Self Charging Hybrid) to sell important products is one of many examples where the media & advertising can seriously sabotage what we need to do urgently.

Image of Apollo13 astronauts racing the clock to save their lives in a crippled space ship using duct tape & whatever else they could find

Simplified Definitions of Units

Volt [V] = The force that push electrons through a conductive material

Amperes [A] = Refer to the volume of electrons being pushed through a conductive material, (i.e. current).

Newton [N] = A measure of force. 1 Newton is what you feel when holding still approximately 1/10th of a kg mass on planet earth

Joule [J] = A measure of work done. 1 J of work is done when 1 N of force is used to move a mass for 1 meter of distance

Watt [W] = A measure of power or ability to do work. 1 Watt is equivalent to 1 J of work done in 1 second of time (speed of work)

Watt [W] = In electric machines this is the multiplication between Volts and Amperes. When increased power is required, designs aim for highest voltage and lowest current to achieve best efficiency

Kilo Watt [kW] = 1000 Watts

KiloWatt hour [kWh] = Measure of total energy used, stored or delivered. A 10 kWh capacity battery can theoretically deliver 10 kW for 1 hour or 5 kW for 2 hours.


1 Toyota UK website, technology explanation; We Choose Hybrid, Join Over 10 million Toyota Drivers; www.toyota.co.uk/hybrid/

2 Tim Pollard, Car Magazine (2017); Toyota has sold all its shares in Tesla - here’s why; www.carmagazine.co.uk/car-news/industry-news/tesla/toyota-has-sold-all-its-shares-in-tesla---heres-why/ (accessed 17 April 2019)

3 Toyota Europe News Room article (2017); Worldwide Sales of Toyota Hybrids Surpass 10 Million Units; newsroom.toyota.eu/global-sales-of-toyota-hybrids-reach-10-million/ (accessed 18 April 2019)

4 Norihiko Shirouza, Reuters News (2019); Toyota Sells Electric Vehicle Technology to Chinese Startup Singulato; uk.reuters.com/article/uk-autoshow-shanghai-toyota-singulato-ex/exclusive-toyota-sells-electric-vehicle-technology-to-chinese-startup-singulato-idUKKCN1RR0QV (Accessed 19 April 2019)

5 Lexus Europe advertisement on YouTube (2018); Self Charging Premium Hybrid Range | Lexus 2018; www.youtube.com/watch?v=ucOH_TLt1oQ&feature=youtu.be

6 Sarah Keller, The International Council on Clean Transportation (2016); A World of Thoughts on Phase 2; www.theicct.org/blogs/staff/a-world-of-thoughts-on-phase-2 (accessed 10 May 2019)

7 Sixty Symbols YouTube channel (2018); The Greenhouse Effect Explained; www.youtube.com/watch?v=hUFOuoD3aHw (accessed 14 May 2018)

8 Vehicle images from respective OEM websites & Wikipedia

9 Meme sketch is of Phillip J Fry from the science fiction series Futurama

10 Image of chicken in wolf's mouth; www.maxpixel.net/Food-Mongolian-Wolf-Wolf-Predator-Prey-Mongolian-1758231