Check all on the onboard electronics. They were state of art back in the day, but now, not so much. Most parts are still available, just getting a little pricey. Can't say enough about the performance of the 4.9 V8. Tons of power, relatively good fuel milege but you do have use premium gas.
If this car wasn't so great looking I'd had gotten rid of it a long time ago. I've owned many GM cars and even a Dodge and VW Rabbit and this car has had more things go wrong with it then I have ever had with any other car. Major things like the on board computer, the fuel tank and fuel pump had to be replaced twice, A/C stopped working, and now the injectors are going bad. It has 97,000 miles on it. good points....gets excellent gas mileage even in town I average 20 - 23 and on the freeway at 65 mph I get around 28 to 31. the engine is very powerful and responsive. bad points there is always some little thing breaking down and repairing this car is very expensive UPdate: did major tuneups and replaced idle sensor control & electronic module it now runs like brand new Update; 9/23/16 finally after three different garages and mechanics and six months (they all told me something different) an older mechanic figured out I needed a new electronic module...a $30 part. Now the car never dies and runs great.... March 2017 this car should be called F O R D fix or repair daily engine runs great but nothing else wants to work
i bought my DeVille from a private seller on October 15, 2010. I am 20 years old and needed a car to get me by from point A to point B. The DeVille did better than that. I am very fortunate to have found a comfortable car and one that is fuel efficient. All my friends are amazed at how smooth it runs and steers. I am very satisfied!
Has a lot of "under the hood" work to get done but is decent enough from point A to point B.
I thank Cadillac is the best car on the highway this is my 4th one and it has never let me down yet if the belt breaks it keeps on going .It has the best performance on highway. The other night the pulley on the alternator broke and it took me back home, it just stop charging. I really do like Cadillac don't want to drive anything else.
Power door locks, adjusting seat,power window, I can unlock doors through the trunk when I shop.
Improvement I can't think of any ,maybe the seat belts should come over the shoulder of the seat.Cadillac has a great performance.