Any sarcasm wasn't directed at you,merely the fact that these things are still around.....yeah good point minus the bad sarcasm... another redex for modern car type scam then...
that's bcuz it is such a easy way to improve fuel economy, if one mfg implements it to get an upper leg, then everybody will do it, and they all end up in square one. They got to keep arsenals like this in their pocket (along with 100psi tires) so that when they are forced to increase fuel efficiency, one of these bags of tricks will be pulled out once in a while.
works or not, but if fuel saving does not sell cars, then they won't put 5 pence of R&D into it.
The point though was that there is no evidence that this thing works in any review or test,and that was the subject of the original question.....over on this side of the pond,where fuel is way more costly than your side,manufacturers DO put a lot of work into making small,economical cars(as well as the big thirsty ones) because the little ones with good economy DO sell.
