According to the BBC:
tyres will be graded from best-performance - green A class - to worst, red G class.
That sounds strangely familiar, though of course HIPs have nothing whatsoever to do with EU Directive (2002/91/EC), because 'trusted' news outlets like the BBC failed to mention it, so it can't be true.
The most obvious way of improving a tyre's fuel efficiency is to lower the resistance, and this can been done with less grip and making them thinner to reduce drag.
So no prizes for guessing what grading will be used for the 225/40 R18 tyres which my car requires.
One wonders how long it will be for taxation to be introduced to reflect the tyre's graded performance, especially given that President Rompuy-Pumpy appears to be so keen to introduce direct EU green taxes.