I love my 1991 DeVille for comfort, beauty, smooth ride. I save money on hotels because it is so comfortable I prefer sleeping in it to sleeping in a hotel bed. The gas mileage was fine when I got the car used in 2000. But see the favorite feature below. Cadillac repairs are notoriously expensive no matter who does them but until the car was 16 years old, I needed almost no repairs. It was super. Then, at the 16-year and around 100,000 mile mark, the car started to self-destruct, one part at a time, so that I kept sinking money in being reassured that each repair was the only apparent problem. So be really careful if you own or are looking at one of these models now.
What I love is the instantaneous mileage meter that allows me to adjust the accelerator to get better gas mileage as I drive. I usually get instantaneous mileage of between 18 and 28, depending on the terrain. Also, I love comfort. I want to convert it into a spare bedroom once it can't be driven.
Just wish it would last longer. I love everything about the car if we consider how it would have been when it was new.