The Ultimate petrol fuels are the only thing I ever use in the ST, much better for the engine with better economy (although that would't be hard!) and more power.
The Ultimate diesel fuel is amazing, and takes a lot more effort to produce than the petrol. Well worth it though, I used in my truck (when I was a driver) and I would regularly get another 100 or so miles out of a tank! It also smoothed over a few dead spots in the lower end.
Note: it had a 205 litre tank
