Energy nonsense

There are lots of roads around so wouldn't it be great if they could generate electricity? One brilliant idea is to use thermoelectric junctions that generate electricity when the tar gets hot with the sun. Apart from the poor efficiency and lack of sufficient sun except for a couple of months the delicate junctions would soon get torn up.
Then there is the idea of using piezo electricity so that the compression of the road by cars will generate electricity. The power is stated to be 400kW per kilometre of dual carriageway. Very impressive. However the road would have to be made slightly spongy in order to absorb energy from the cars. So the net effect would be to make cars roll less efficiently. It is effectively the same as if the tyres had been under inflated. The Environmental Transport Association says that if all the UK's motorways were installed with this system then it could power 34,500 small cars.

So lets look at the claim a bit closer:
400kW?
Take 4 lanes
at 60mph
over 1km of dial carriageway.
Makes 4km of lanes.
Assuming a fully packed road, at 70mph the car spacing is about 80m.
So the total cars on this road are 4000/80 which is 50 cars.
So they say they can recover 400kW/50 or 8kW per car. Huh????

Shame on the Stroud News and Journal and other places that just published this nonsense without checking.