I bought my 1996 Cadillac DeVille used in9/04. It had nearly 100,000 miles on it. I had problems right off with misfiring, which ended up being faulty plug wires (which had just been replaced??). I'm glad that I didn't have to pay for them! Also, the air conditioning didn't work. It took $200 to find a bad wire! Have put 20,000 miles on it since then without any major issues, which is a good thing because it costs a boat load to fix the thing! The previous owner burned 87 octane fuel and so have we-don't notice any performance difference even when we did try the expensive gasoline.
Amazing gas mileage on the highway for this size vehicle, Ihave done as well as 28 mpg at 70 mph! I travel to work is about 12 miles with 7 stoplights and/or stop signs and it still averages about 21 mpg. Lots of room-this is a big, solid car. The seats are nice and comfy! Lots of rear leg room!
It burns oil like crazy - a quart or 2 every 600 miles! Get reasonable with repair prices. The EGR valve needs replacement now. I've got the got the "service engine" light on now. The suspension is too soft and "boaty" for Maine roads!