[Adrian E]

Originally Posted by HPsauce

That's actually quite odd, given that adjusting for fuel quality/RON with knock sensors etc. isn't exactly new technology. And it's an "S" Audi.....

Both my S8 and the much newer Volvo say specifically that they get best performance (and fuel economy) on 99RON fuel but can run on 95. And they do! Cost per mile is I think certainly no worse on Tesco Momentum than on standard 95 and since E10 appeared, which has worse efficiency, I suspect the balance is now in favour of E5/99.

A nice option, if not too expensive, would be a map that takes advantage of E5 with better performance and economy, but will equally run without complaint on E10.

Indeed - the RS models will still specify (I believe!) 98 for best performance but will run OK on 95. The S models (the ones I've seen that are later than the D2 anyway) simply say 95 and do not specify/mention 98 at all. I think MJ has mentioned her experience with this batch of vehicles too, but I've found on tank averages that there's no appreciable performance benefit and no measurable improvement in fuel consumption by running a car intended to be run at all times on 95 on 98.

A lot of it is down to advances in other parts of engine/management design, plus changes in perception over fuel grades in Europe, so if you can safely produce the power and associated driveability on 95 then that's what is specified by the manufacturer.

My dad's car is one of that select band of vehicles post 2000 that cannot use E10 fuel (2006 Lexus IS250) so he's having to remember to fill up with E5. Luckily his mileage these days is tiny so he probably only tops up every couple of months.

Agreed that a map that covers both (but delivers the majority of the benefits on E10/95) would be ideal scenario.