I am set to buy another EX-V6 in the next few days.

Questions,
1. How is the quality of 06 Accord EX-V6? Should I consider to "upgrade" the tires while negotiating? My 05 tires seems OK to me.
2. From a Mazda forum (Mazda 3sGT was on my list before deciding on Accord again), several people are complaining Mazda 3 AT EPA rating is WAY over reality and they concluded part of the reason was the 17" wheel. Is 17" vs 16" wheel really making such big difference on gas mileage?

the HEAVIER your wheels, or just the heavier you car is in general.. the lower the gas mileage you will get. hondas quality is unrelenting (in general), and if you put a cheap ass $600 total package tires and wheels that are heavy ass on your car......then yea you can expect your gas mileage to go way down. its about inertia.

my girlfirend's brother has a mazda 6 with 17's (factory rims) and they look freakin' heavy, nevermind just plain bad. Heavier wheels will suck up gas mileage; you'd be surprised. If you pay for cheap rims, they really won't give you any performance gains. Honda seems to be pretty consious of their gas mileage though. Their upgraded rims probably kick mazda's butt.