Twin Engine - the name says it all. Or does it? Uhm no, actually not, weirdly. In fact the whole setup has one engine and two motors. Let's see how all this works in general with the T8, the latest and most powerful Twin-Engine powertrain, which offers up to 415 hp in the Polestar Engineered S60. Not too far off from an M3!
The core-part of it all is of course Volvo’s 2.0l turbocharged and supercharged four-cylinder petrol engine - which is a masterpiece, period. You really should, no you have to watch Jason's perfect explanation of how this works, on Engineering Explained.
Between this engine and the gearbox sits a small electric motor, sending 46 hp to the gearbox along with 110 lb-ft of torque. It also helps to start the engine, power the accessories, and provide regenerative braking.
The second electric motor is mounted to the rear axle and provides all of the drive to the rear wheels adding 82hp and 177lb-ft, all whilst measuring just 25 cm in length and diameter, a capable little fellow! So yes, the rear wheel drive is completely handled by the electric motor alone, in fact there is no physical connection whatsoever between the front and the rear part of the all-wheel drive system. This lack of a driveshaft makes it simpler and cheaper to adapt the powertrain between sedan, estate and SUV, or whatever other body styles and wheelbases they would want to put it in in the future.
With a conventional AWD system, you need to mount a transfer case, a rear differential and a center driveshaft. All of that adds weight and complexity and to put those parts into a different car, even on the same platform, you'll need to find places to mount them at first - not the easiest task. With the T8’s rear electric motor driving the rear wheels directly, the only extra components needed are some wire (to put it impertinently simple).
The weight savings do help to get an electric-only range of over 30km, better than nothing I'd say. Less weight is of course good for performance too and so is the disconnection between front and rear drive: When one power source isn’t at its peak, the other one is; this leads to a more effortless acceleration.
The big orange block are the batteries.
Another advantage of having no driveshaft is to have some space left down there to use for the 9.2 kWh batteries. Therefore the centre of gravity is lower (which doesn't only serves for more driving pleasure but also is good for safety) and you're still able to load all your IKEA furniture in your Volvo since the boot stays untouched!
You can make use of this system by choosing one of three drive modes:
"Pure" keeps the vehicle in electric-only mode. You can drive at speeds up to 74 mph without using any gasoline.
The "Hybrid" mode drives much like any other hybrid. The car figures out how much gas and how much electricity to use for optimal efficiency.
And then there’s "Power", to give you all the power and fun available!
But there's a problem with the T8...
...it's freakin expensive and only available with the SPA platform, which means 60 and 90 series cars - and let's face it, not everybody can afford them.
So there's also the T5 Twin Engine, the budget version of this system, made for the 40 series cars. It works quite differently though since it only has one petrol engine and one electric motor, and therefore front wheel drive only instead of all wheel drive. Apart from that it uses a 1.5L turbo four-cylinder engine and produces "only" up to 247hp and still impressive 295 lb-ft.
The electric motor isn't crammed between the engine and the gearbox, instead it's really intelligently combined with the dual-clutch gearbox:
As all dual-clutch gearboxes do, Volvo's have two input shafts, individually operated by each clutch. So gears 1,3,5, and 7 are mounted to one shaft, 2, 4, and 6 the other, not too special yet. But Volvo connects the electric motor to the 2,4, and 6 gear shaft. Meaning, when the petrol engine is off, the T5 drivetrain only uses those three gears. But petrol engine and electric motor are working together most of the time and the engine can either power the odd-numbered gears on the one driveshaft at the same time as the electric motor turns the other one, or they can both power the same even-gear shaft.
Aaah the Swedes, an innovative and quirky people you gotta love!
Volvo doubtlessly made some great engines in the past and the 5-cylinders have become legends quite rightly by now. However I think both the T8 and the T5 are magnificent machines. I hope someday I'll have the opportunity to drive for instance the Polestar Engineered S60 to experience this clever combination of electric and petrol power myself.
But what do the Volvo people of Drivetribe say?
Are you excited of all the new Volvo tech or would you rather go back to the classic inline-5?