High octane petrol – no difference unless you have a turbo or a high compression ie actual sportscar engine.
Higher cetane diesel affects any diesel car regardless. I thought V-Power/Ultimate was higher cetane as well as cleaner? Higher cetane supposedly gives better starting, smoother running, better power and better economy.
Anecdotally, in my Passat, the fancy stuff runs a bit quieter and definitely starts better. However, starting on normal is never a problem anyway. I can’t tell if there’s any more power, and any improvement in economy is lost in the normal variation so I can’t tell. I don’t drive the same route regularly in the same conditions.
I’ve also noticed that normal Total diesel is pretty smooth, and doesn’t cost extra.
Isnt maximum torque where the engines most efficent?
Not really – depends on loads and loads of things, including engine load. And how you define efficiency. Fuel/engine power ratio, fuel/speed or fuel/distance…?