Car use and prices in UK

It's useful to have such figures as this to hand, relating pricing of fuel to car use.

If the real price of fuel goes, and stays, up by 10%, the result is a dynamic process of adjustment such that:
a) The volume of traffic will go down by roundly 1% within about a year, building up to a reduction of about 3% in the longer run (about five years or so).
b) The volume of fuel consumed will go down by about 2.5% within a year, building up to a reduction of over 6% in the longer run.
The reason why fuel consumed goes down by more than the volume of traffic, is probably because price increases trigger more efficient use of fuel (by a combination of technical improvements to vehicles, more fuel conserving driving styles, and driving in easier traffic conditions). So further consequences of the same price increase are:
c) Efficiency of use of fuel goes up by about 1.5% within a year, and around 4% in the longer run.
d) The total number of vehicles owned goes down by less than 1% in the short run, and 2.5% in the longer run.

And then there are effects of income:

If real income goes up by 10%:
a) The number of vehicles, and the total amount of fuel they consume, will both go up by nearly 4% within about a year, and by over 10% in the longer run.
b) But the volume of traffic does not grow in proportion: 2% within a year and about 5% in the longer run.

Longer term effects differ, of course, because decisions and processes involved in buying and selling cars or shifting travel patterns can and do take some time as people think about their lifestyles in relation to shifting realities outside of their control.