Tom Anderson wrote:

Actually, the real cost of motoring *has* gone down, hence (partly)
the
growth in the number and length of car journeys.

I didn't realise that! How the hell did that happen?

According to:

http://www.barrydoe.co.uk/2004.pdf

Between 1970 and 2004:

Inflation has gone up 10 times
Price of petrol has gone up 11 times
Average earnings has gone up 19 times

So, the price of petrol has, in real terms, been virtually static,
whereas average earnings have gone up almost twice as much as the price
of petrol.

Therefore, combined with the huge improvement in vehicle efficiency,
the average person can 'afford' to travel a lot more by car in 2004
compared with 1970.