Why a smaller engine doesn't mean better fuel economy every time
Quite a common misconception amongst everybody
There must have been times when you thought you have chosen the ideal car for your future (let's say a Range Rover Velar with the V6 the sake of this story), then you show it to some of your friends and family to see what they think about it, only for in return they say on the lines of: "Gosh, an 6 cylinder, good luck spending your time at Shell" or "pick a smaller engine. It won't hurt you instead benefit you". You get the idea.
Taking the RR Velar is a good idea. With a very diverse engine choice from a 2.0L 4 cylinder to a supercharged V8, it has it all.
Generally when you think about big engines, probably one of the first things you think about it is that its going to sip fuel like a thirsty dog, and a small engine would be more gentle on the liquid as it has got less cylinders to sweep through less engine volume.
Or is it?
With a bigger engine, a lesser proportion of its power output is required for it to do what its required to do then, such as accelerating to motorway (highway/freeway) speeds from standing still at a stop light, meaning the driver only needs little throttle input to do that in a conventional time period, allowing less fuel to be burnt as RPMs are kept low.
With a smaller engine in the same car however, using the same example used before, to get the car up to speed of the road from a standstill in the same time as how the bigger engine one does it in, a higher proportion of its power output is required as power to weight ratio is worse, meaning more throttle input is required from the driver to build up RPM and speed, resulting in more combustion of fuel.
So theoretically, although the bigger engine is the more fuel inefficient one, with the needs of driving these days that constantly require that little gain of speed in a short span of time, whether its getting the car to move from a standstill, overtaking someone or accelerating to a higher speed limit, more strain is put on the smaller engine to get the power needed for the car to do the same task as the one with a bigger engine which is naturally has a better power:weight.
However, this case does not apply to cars with a well-balanced P:W ratio, such as small cars with small engines like a Subaru BRZ where the power is suited to the weight of the car.
So enthusiasts, y'all can keep your big engines without having the thought at the back of your head consistently telling you to switch to a smaller engined car to save costs. Sometimes.
Thanks for reading.
Thoughts on this? Comment below!