Here is a worked example of lightweight, aero, simple and cheap.
Lightweight
The shell was designed to be light from the outset and it used plastic for quite a few of the external panels including the bonnet. External panels are also made of very thin metal.
Aero
Overall style came from the eco2000 concept project that PSA had been involved in. Cd at the time was 0.31 - this is the mid 80s.
It was very much simplified for mass production though as you can see. The 3 door models had partial rear wheel covers (a Citroen style item at the time) and recessed door handles. They all ran on skinny tyres too, and no huge grill openings at the front.
Simple
No fancy engines (4-cyl, OHC 8vs), not even fuel injection on the Mid-80s ones - engines shared with the other PSA hatches - the 205 and were lightweight aluminium units except the later Diesel which was modified to be an iron block for reduced noise. The underpinnings were all recycled from the Peugeot 104/Citroen LNA/Talbot Samba.
Cheap
Sold down to a price to compete with the equivalent hatches at the time. It was intended to replace a few cheap cars from the various companies PSA had 'acquired' including their own Visa, the LNA/104/Samba trio and there were even thoughts it could finally replace the 2CV which was getting expensive to build.
The result of this cleverness was a car which could outperform its competitors whilst having a smaller engine. The 1.0 base model could outrun an equivalent Fiesta 1.1 and was capable of over 90mph. The 1.1 model could keep up with a Fiesta 1.3/1.4 and could do 105, and the 1.4 could challenge an XR2.
And good on FE - the 1.5 Diesel has a combined MPG of 78.
Downsides ? Well the lightweight construction led to it feeling a little flimsy after a few years use, and of course it is described as 'not too clever in a crash' - but it was never regarded as a death trap at the time.
With a little imagination maybe makers could still come up with something like this ? Well maybe not. All those safety features we insist on seem to have put paid to that idea in small cars anyway. This is the AX's grandson :
The modern equivalent, the C1, had to be designed (mostly by Toyota) to get the weight down, but its still quite lardy. And there is no Diesel anymore at least in the UK, just a 1.0 68hp Petrol which sounds like a 911 apparently
