FWIW, I average about 25-26MPG with 75% highway driving. If I drive 100% highway, I get 29MPG. The car revs at about 3200RPM at 80MPH, so I can't expect much better.
What everyone else says is correct, the main weak points of the SVT are the water pump and the transaxle.
If you find one with more than 75K or so, chances are it's had the water pump replaced. Hopefully through preventive maintenance, but more typically after a failure (hopefully one where the driver didn't let the car overheat).
The typical transaxle issue is the spider gears blow after a hard launch. No way to tell if the car's been abused that way, but if it doesn't make any noise and feels smooth you have to take the leap of faith.
There are cold shifting issues as well, but these aren't a big problem and can be reduced using CEG's tricks.
Happy hunting.
