I'm trying to figure out why I'm getting such bad gas millage. So many people say just replace the O2 sensor. I'll do it, but what confuses me is that the car really seems to drive and respond well. I've never had a VR6 before, but compared to the 16v I just sold it drives well. Also, when the 16v had a bad O2 sensor, it really shows in hesitation on throttle. So would the VR6 be the same, or does the bad O2 sensor just cause improper fueling with leads to less power and bad millage?