For a Maryland driver just outside of Baltimore with a clean driving record , and a $ 1000 deductible collision and comprehensive insurance , I got $ 233 month for a ' 07 Z and $ 199 month for a G 35 coupe through ProgressiveNot sure why the G 35 would be cheaper . I ' m assuming because it has a backseat and is considered ' less ' of a sports car than the Z . Sound quality in a Z isn ' t bad , no real droning . You can noticeably hear the engine however . I have an HKS exhaust and a JWT intake on mine and I don ' t mind it at all I drove it from Baltimore to Myrtle Beach , SC with no complaints . There most likely louder than a G 35 . Again I can ' t speak for a G 35 but I ' d guess since it ' s more of a luxury car there ' s probably more sound deadening in the interior .