I have owned both, the G is a more forgiving car on the race track, but if you know how to hustle a car like a go kart and leave the a$$ end out you can make the S2000 faster.

The G has more room and is more comfortable. Taking trips in a S2000 sucks, you and significant other can only pack a backpack full of clothes for the trip, and it's loud on the highway.

S2k does get better gas mileage.

S2k's eat up tires.

If you park outside, S2K's suck in the winter.

S2k OEM radio blows donky di@%

Both car's accept mods well and have a strong aftermarket.

S2k's have to have the valves adjusted every 30K and is an expensive service at the dealer

thats all i can think of for now