[Cameo White]

I second Citcapp. In Illinois (at least the Chicago area, and I think the metro east around St. Louis), the fuel mixture is changed for winter (increased oxygenates, I was told, supposedly to help reduce pollution, since the cold air can trap it next to the ground for days on end). My 2004 Vue (Honda V6) drops off by anywhere from 5-10 MPG per tank (worst when it is real cold), down to around 10 or 11 at times, in city driving. The falloff isn't as bad on the road. Some of this is due to increased warm up and idling etc, but the same thing used to happen with my 94 Cutlass Supreme convertible that had the 3.4 DOHC V6. The explanation I read somewhere a few years ago is that the increased oxygenates in the exhaust passing by the O2 sensor cause the computer to dump more fuel through the system. There may be less pollution from oxides of nitrogen this way, but there is probably more from unburned hydrocarbons getting through. Anybody else see this? I think maybe it was in Car and Driver at the time, but it has been several years and I may not be remembering it all correctly.