A while ago I attended an electric car show held in Sydney. I made the 2000-odd kilometre trip in my Peugeot 405 diesel, a car that, incidentally, gained high Fives (in litres/100km) for the trip.

At the show I briefly sampled three of the home-converted electric cars – a very interesting experience. And on the long drive home to the Gold Coast, I had plenty of time to reflect on these cars.

The electric cars I drove each retained the original gearbox: the electric motor was bolted up to the ‘box and the ratios could be selected by the driver. Typically, the cars were started off in second gear and then third and fourth and fifth gears were used as appropriate. (I used first gear off the line and felt an immediate gain in starting performance.)

But none of the cars I drove had performance that came close to conventional petrol engine (or even commercial hybrids). Even when the electric motor was rated at a higher power than the original engine, the massive weight of batteries substantially dulled the resulting power/weight ratio.

Putting in a more powerful electric motor (or running two electric motors) would of course help solve that, but at the expense of greater electrical power consumption that in turn would need either more batteries or result in a shorter range (and none of the ranges were very good to start with!). However, all the cars could easily exceed the 110 km/h open-road speed limit.

Clearly, what is needed is an electric motor that has only enough power to do the job – but no more.

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Imagine you were living in the late 1930s (and of course, a very small number of you may well have been!). Then, as now, cars had four wheels, a body, engine, suspension and brakes. But they often had something else as well – a chassis.

Nowadays, nearly all cars use monocoque construction, where the pressed steel body provides the required stiffness. The main exceptions are traditional off-road four-wheel drives and trucks and buses – these vehicles still largely use a separate chassis. A few bespoke cars also use non-monocoque construction; for example, a tubular space frame.

But even in the late 1930s, you could have seen plenty more designs that just a traditional chassis. Have a look at these – all are taken from The Mechanism of the Car, written by Arthur W Judge and published in 1939.

Firstly, we have monocoque (or unitary) construction. This Vauxhall retains a separate bolt-on chassis for the front suspension and engine mounts, an approach common in cars up to the 1970s.

But then we have the cast aluminium frame. What?! Yes, a car being sold in 1939 (the Hotchkiss Amilcar) used a frame formed from cast aluminium members bolted together.

Here’s how the cast alloy frame integrated itself into the car.

Then there was the tubular frame, as used by Austro-Daimler. The very large diameter central tube would have given both high bending strength and also resisted torsion.

And finally, we have a car that’s absolutely intriguing – and one I’d never heard of before. It’s simply listed as the ‘MG Racing Car’ and uses a backbone chassis formed from pressed, welded plate. The car also features double wishbone suspension front and rear – perhaps the first car to ever do so.

I think that these drawings are worth looking at closely (you can click on them to enlarge). In mechanical car design, there’s very little new under the sun…

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