Premium vs ordinary unleaded

Hi all

I hav just recently (about 3 tanks full) started running premium in our little Holden Nova twin cam (1989) but not EFI. The result is that I am getting at least 10% better fuel economy out of it. Given that the premium costs only about 5% more, It seems to be a win win situation. I think the car is running better too, idling smoother. Now getting about 9.8l/100km from a tank, and that is running with the a/c on a lot of the time because of the baby. All is around town stuff too. Not bad I say.

My question is though, are there any drawbacks? If not, why are we running standard unleaded at all, assuming most cars will get better economy and running/performance? I also understand it burns better and produces less pollution. Almost no-one according to the servo guy I spoke to uses premium (unless in high performance or really late model expensive vehicles requiring it) It may be that people can't look past the lower price of ordinary unleaded, can't see the longer term savings than at the time at the pump.

I know that premium is unavailable at many remote spots, but for around town it sounds like the go.

D-Jack