Foz
Active LVC Member
when I picked up my ls it was averaging 17-19 (last sept) depending on how much hwy driving I was doing... I stay on top of the oil, have changed the air filter. every few months I notice it drops a mpg, I'm down to 14 now! 6 months ago I replaced the valve cover gasket, a coil and all the spark plugs. it got better for a week or two, but ended in the 15teens? I haven't touched the fuel filter.. but I am really curious how it keeps getting worse? Oh and I changed the thermostat a little over a month ago. the car is an 00 V8 w/67K, I bought it 13 months ago with 53K... It seems to run good so I don't really get it?