dougbrainerd Posted March 30, 2008 Report Share Posted March 30, 2008 Hello All. In my owners manual it is stated that the 2000 Deville, standard engine will run fine on regular 87 fuel BUT for optimum performance use high octane. I used to buy premium but when fuel prices went nuts 2 years ago I switched to 87 with no noticable difference. Last week when I drove it to Myrtle Beach (golf orgy) it was getting 24 MPG on 87 but did 28 on premium. Simple math shows that running premium on the highway is the best value. Another interesting phenom was that the car did better on fuel at 75 degrees than at 30 degrees. Maybe most people already knew these gas facts but I didnt. Golfnut out Link to comment Share on other sites More sharing options...
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