I wonder what improvement in mpg lorries would get if restricted to 50mph on all roads including motorways.
They are at the moment on M6, M56 M62 and M1, AI and A1M ( the roads we used on our trip up to Yorkshire last week ). Trouble is all the traffic was limited to same speed by roadworks and average speed cameras
Also it seems on many other motorways the same.
Our road network is a real mess, is seems link the proverbial 'painting the Forth bridge' with roadworks, contra-flows lane closures etc. etc.
Mind you it did wonders for MPG on Civic 1.8, at one time indicated over 49mpg average, came down a bit over Pennines though, but still over 47 for whole trip of 750 miles ( visited Bamburgh Castle and came back via Matlock )...