I don't believe it.

But if I normally get 60mpg, that's about 20km per litre. So to drive 80km without a flag takes 4 litres.

A flag costs an additional 40 litres over that 80km????

I realise they aren't going to be talking about my car.  But it still seems a suspiciously high figure if talking about cars.  What did they test it on?  A Hummer full of bricks?

(Unless, of course, I've got Wednesday morning syndrome and my maths is screwed.)