Larry, I just read your post about vibration and how to determine where it might be coming from. My car has been vibrating at about 55 mph and just today I realized that it was engine rather than road speed that determined when I would have the vibration. I had my tires balanced to eliminate that possiblility. And, while they were out of balance, this did not solve the problem. Today I noticed by shifting into different gears that the vibration was occurring at about 1800 rpm regardless of which gear I was in. When cruising on the highway, I pushed the gearshift lever into neutral several times and the vibration seemed to stop. I feel that this indicates that the vibration must be coming through the engine. The last trip I took in this car I recorded 30 miles per gallon; so, I wouldn't think that the engine is out of tune. Is it possible that a spark plug, a wire, or some sensor may have gone bad since my good gas mileage? Any help would be appreciated. Thanks for any assistance, Big Ron