Engine pozzie no laughing matter

The Mini was a revolutionary front engined car. Photo / APN

For decades cartoonists and comedians have made mileage from cars that don't have their engine at the front. A hapless motorist looks under the bonnet of an original Volkswagen Beetle for the missing engine - everyone's seen or heard them.

So why is it that some designers put the engine in the middle or the rear? They can't all be relatives of joke-makers looking for material. Engines have been in the front ever since horses and bullocks did the work.

Although some pioneers flirted with other locations, Ford's Model T well and truly established the front-engine configuration. That location has stood the test of time, its nose-heavy weight distribution being the only big drawback. These days, we have engines in the front driving the front wheels, the rear wheels or all four wheels, a truly adaptable and universal arrangement.

But there has been an influential group of companies and designers that favoured rear-engined cars as a way of putting extra weight - and thus traction - over the driven wheels, and also as a way to cut costs.

Years ago it was easier to get more traction this way than with the now ubiquitous front-wheel drive, which added the complication of having to also steer the wheels. The rear-engine configuration saved manufacturing costs as the entire engine and driveline could be assembled as one unit and slipped into the body.

VW's original Beetle is the enduring symbol of a rear-engine, rear-drive car, although others were developed at about the same time. The downfall of the rear-engine, rear-drive configuration was its oversteer handling characteristics. In a corner, the rear end wants to swing wide, especially if the driver brakes or lifts the throttle. This is what killed the American Chevy Corvair, the car deemed by consumer advocate Ralph Nader to be "unsafe at any speed". Experienced drivers often enjoy oversteer, but for many others it was a quick and easy way to a crash.

Engineers and tyre designers lessened but never eliminated oversteer.

Front-wheel-drive cars have the opposite characteristic, understeer, regarded as more benign and able to be handled by the average driver.

You might think the rear-engined car would have faded away, but it didn't. Porsche persisted in the 911 series, in later years teaming it with all-wheel-drive. At the other end of the cost scale, the Indian Tata Nano, the world's cheapest "real" car, has its little engine in the rear.

So if a front-engine car understeers and a rear-engine car oversteers, a car with its engine in the middle would be just right, right?

It's easy to achieve perfect weight distribution by putting the heaviest component in the middle, improving stability, and honing responsiveness by reducing the vehicle's moment of inertia. But from any packaging perspective, the middle is a lousy place to put the engine, pretty much limiting the configuration to two seaters. Engineers responsible for efficient cooling are challenged. It also limits access for maintenance, but no more than all the vans with their engine "under the driver's seat".

Although many mid-engine designs have the powerplant immediately behind the passenger compartment, it doesn't have to be that way. Other designers have opted for a front mid-engine configuration in which the engine is placed well aft of the front wheels - British TVRs of the 1970s used this arrangement particularly well as do some modern family cars.

Mid-engine cars can be great fun to drive but they need to be watched on wet or slippery surfaces. Although the configuration is said to offer some traction advantages, they could break away quite easily. Today's ESP and traction control have tamed that characteristic. Such electronics could pave the way for a widespread return of the rear-engine car. If that happens cartoonists and comedians only need dig out their old material.