We run all our cars on either Shell Unleaded or Shell.V Power. The simple reason is because it is better for the cars. I ran Tesco unleaded once in my old nova, and had to sifen it out again, it clearly didn't like it! And that was standard at the time. My dad has a Vectra 2.2 Sri which benefits from v Power but as the price is higher Tm we use regular shell, but as we are part of the v Power club we still get some points for snacks or free fuel. But on my dads opel manta GT/E exclusive, we always run v Power. Anything pre 1990 will probably benefit from v Power, with mechanical Ecu or carbs. My dad's car originally ran on 4 star, timing was great and managed 220bhp. When the timing was changed to accommodate unleaded back in the day, it lost about 40-50bhp, now Super Unleaded is available we adjusted the timing back and all the power is back, and throttle response is as sharp as ever...