I have no figures to substantiate this but the divergence between the UK GDP and road traffic miles does correspond to the peak period of 'gentrification' when run down working class housing in city centres was taken over middle class incomers and tarted up.

As a result pubs became wine bars, greengrocers became delicatessens and the church halls started having ballet classes for children instead of bingo sessions for pensioners and property prices shot locally up much faster than the average for the country. It became a middle class sport to spot the next area that would be gentrified so that you could get in quickly while prices were low.

This was helped by the housing stock being largely brick built and therefore usually structurally sound despite decades of neglect but most of the most promising areas were done over some ten years or so ago.

So the theory would be that since the middle class were busy rehabilitating cities rather than building out on the fringe the typical relationship between miles and GDP was broken.  Interesting.
I worked on a fair amount of gentrification in the late 70s/early 80s in Takoma Park, Woodley/Zoo, and other areas of Northwest DC.  So many places were going condo that the renters weren't too thrilled to see us show up with measuring tapes.  There was a lot of infill, too, like Foxhall Crescents on the old Rockefeller land.

Of course, we were building new towns and suburbs like gangbusters, too.