I doubt you will see anything better than 26 on the Highway. Remember,
you have a real havy car for the power. I run Bosch Platinum +4 plugs.
With a compete tune-up, I was able to get 26 with the windows up and
the heater on (it was February). I average 20mpg city/highway. The 97
isn't a whole lot sleeker than my 89, but it is heavier.
Shoot, they come rated around 24mpg from the dealer.