How do you people get so good of mpg with your SSEi'*? The best I've ever gotten was 26 mpg. The last month it'* down to 13 mpg. 240 miles max and I put in 17.9 gallons.
I don't do a lot of in town driving, maybe 40 miles out of the 240 miles. I try to baby it and it still doesn't get over 250 miles and if I'm luck 260. My parents have had two Park Avenue Ultra'* (both Series 1 SC'ed) and the best they have ever gotten was 25 mpg on a trip to the Grand Canyon, but generally in the 20-22 mpg range. My sister has a 1995 Riviera (Series 1 SC'ed) and the best she ever got was 22 mpg. My cousin has a 1996 Riviera (Series II SC'ed) which he totally babies and on a trip to Milwaukee he got 27 mpg, otherwise he gets 22-23 mpg. My friend'* (he doesn't baby his) 1995 SLE and he gets 17-19 mpg on 89 octane.
All of us put the majority of the miles on out of town (we all commute 15-35 miles one way to work except my parents -mom'* been semi-retired since she had her third kid in 1970 and dad drives his 1990 Olds 98 for work 23-26 mpg).
The 3800 car that got the most consistant mpg that I am familiar with was my dad'* old 1989 Lesabre Limited. It didn't matter how hard, how long, or how often I put my foot into it, or how much city driving there was -it never failed to get below 27 mpg. The majority of the time it would get 30-32 mpg and on a pure highway trip would put out as much as 35-36 mpg. That is one 3800 car I wish I had now with the prices we're paying for gas. My sister and her husband have the car now with over 240,000 miles and last week my sister commented that she just got 32 mpg -made me want to cry.