Engines and Drivetrains Explained

by : Darren Cottingham

Where do they go and what does it mean?


Lotus EliseWhile the majority of cars have their engine over the front wheels, which allows better carrying capacity, mid-engine cars offer a more favourable weight distribution. The engine usually sits just in front of the rear axle, behind the passenger compartment. This usually means that mid-engine cars are two-seaters as the engine intrudes into what would be used for the rear passenger space. The advantages include better handling, better braking (because the rear wheels have more weight over them), improved acceleration (where they're rear-wheel drive as well), and a smoother ride. Because the engine is not directly facing into the wind, vents, air scoops, and additional radiators may have to be used to keep the engine cool. Common mid-engined cars are Ford GT, Lotus Elise, Porsche Boxster and Ferrari 355.


Almost all mid-engined cars are rear-wheel drive (MR), though some are four-wheel drive, like the Bugatti Veyron, and one or two were even mid-engined front wheel drive (e.g. Citroen DS).


McLaren Mercedes SLRA front-mid (FM) engine sits just behind the front axle, and combined with rear-wheel drive gives a better weight distribution than a front-rear (FR) car, where the engine is over the front axle. Examples include the Maserati Quattroporte, Mazda RX-7, Mercedes-Benz SLR McLaren and Dodge Viper.


Porsche 911 CabrioletThe Porsche 911 is the most developed rear-engine rear-wheel drive car in the world, having had over 40 years of incremental iterations to hone its engineering. Rear-engined cars are where the centre of gravity of the motor is behind the rear axle. They're notoriously difficult to make stable because the engine acts like a pendulum, meaning once that back end steps around it's more difficult to control than an excited puppy.


Toyota CelicaFront-engined, front-wheel drive cars (FF) are the safe choice for the average motorist. They understeer when pushed hard, and they give more room in the cabin because the cars don't need a transmission tunnel through to the back wheels. Most family cars are FF.

Toyota SupraFront-engined, rear-wheel drive cars (FR) are the choice for many a sports car and muscle car. Common cars include the Toyota Altezza (Lexus IS200), most BMWs and Mercedes saloons/sedans, and the Corvette Z06.

Four-wheel drive (4WD) or all-wheel drive (AWD)

4WD School BusFWD gives the ultimate grip, but saps engine power with all the extra moving parts. Some cars have viscous centre differentials so that power is channelled only to either the front or rear unless they start to skid, then the diff apportions more power to the other wheels.

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