I've got a 94 bonnie ssei...just bought it this summer and love it...
gas mileage ain't so good in the city...runs good 112,000k
changed the plugs and air cleaner and just noticed tonight that it says to use premiun gas
and i have been using just normal unleaded...
does it make a big difference at all...car doen't ping at all...
and will it harm to motor with normal unleaded..[/b]

No it will not harm the engine really BUT, you'll not get the performance out of it unless you use Premium Fuel! The lower grade gasoline has a different flash point and will over time cause the spark plugs to foul.

Baccala,

Yes it does make a difference in fuel economy as well. The ONE time I ran 87 octane in my car (my wife filled it up, don't ask), my mileage went from 26 mpg (average city and highway driving) to 19. (I live in the country with a half hour highway commute). Try the 91+ (most of us run 92-93 octane). You should be getting anywhere from 20-24 mpg in the city.