Coupe DeVille
The number of miles per gallon that the 1997 Cadillac DeVille can achieve is dependant on a number of factors such as the condition the vehicle is in or the driving style of the driver. However, the Cadillac DeVille is believed to get between 17 and 23 miles per gallon.
One reason a 1998 Cadillac Deville would cut off while driving could be the fuel pump or the car is out of fuel. Another reason could be the spark plugs.
water pump or thermostat housing crack
I have a 98' cadillac deville and it should constantly read around 197-201 when you are driving. It will definitely increase when you come to rest: example at a street light. something is definitely wrong and should be checked.
You have a hole in your brake line.
17 city 26 highway. Expect around 20-22 combined driving.
From all of my experience with cars if a car turns off while in motion it tends to be the alternator.
when overheating occurs at highway speeds the cause is usually. a radiator or coolant circulation problem, Check for a restricted or clogged radiator.
crank or camshaft sensor check for codes put your beauiful car on the neutral when you're braking you'll stop to stall
Idk what exactly u want to know. But i have a 2000 cadillac deville and i put mid-grade in the tank but regular does work fine with no problems. The mpg varies from anywhere between a high 17 mpg to close to 20 mpg because the dash is digital and it changes often depending on your driving. Its not too bad for local driving and the cruise control on mine never worked so im sure by using that you save more gas also. Hope this helped
Your car is more than likely still under warranty, and you need to take it back to the dealer for them to look at it.