In the unlikely event HMRC reduced road tax for fitting this I would get one for the Roadster.
At 5k miles p.a. the payback is too long for 1.5 to 3 mpg increase in fuel consumption as that is only £50-100 p.a.
But if they can get the 30% plus then it seems worthwhile. I have asked them what they can deliver on an ST220 engine.
