I have been using regular unleaded in my g35 sedan, for the first 10,000miles and recently noticed the fuel tank door recommends premium. Should I switch to premium or stick with the regular?

 

This topic has been mentioned quite a bit.

You won't hurt the car.

For optimal performance, Infiniti recommends 91 octane or better. The car runs fine on 87, though with a bit less power and a bit less fuel economy. (Although, with today's fuel prices, 87 usually still gives you a better miles per dollar value, though it's not a significant savings.)