I bought this DTS in 2003 with 114,000 miles from a dealer in MI. The exterior and interior were spotless. They still are other than the driver's seat leather due to my daily driving. All I had to do was test drive a DeVille to know what my dream car was. The car drives solid, accelerates smoothly, and always runs strong from acceleration to passing speeds. I love this car, yet it does have serious maintenance issues. When parts fail, shop around for labor, but expect to spend major dollars on parts. Northstar does burn 1qt oil / 2k mi or so, but is very tolerable as this doesn't seem to have major effects.
Ride is smooth. Acceleration and performance are solid. Appearance is head-turning. Longevity if all maintenance is followed. Bose audio is excellent. Love the lit dash and steering wheel controls. All wood is beautiful and has always been strong in extreme snows. Big car means strong will.
Get parts prices down. Improve fuel economy so car can be a commuter. Improve vehicle design and reliability so car can be owned very long term with low total ownership costs.