Very little, other than general maintenance items like tires, brakes, etc. Only had to replace throttle position sensor (twice in three years). When it goes initially, you lose passing gear/overdrive due to computer being fed incorrect info. Eventually, car will start flawlessly every time, but die when you put it in gear.
Paint has chipped off stupid plastic front bumper that auto manufacturers are famous for any more.
Factory radio quit working, although CD and tape still works fine! It's not antenna connection. Already checked that.
3.8 Liter V6 (232 cu. in. for us die hards who hate metric measurements) is a bulletproof engine. Mechanic I know quite well, before going into business for himself, was service manager for 17 years at Olds-Caddy dealership. He said he regularly sees many GM vehicles (Olds, Chevy, Buick, etc.) with Series II 3.8 V6 come rolling in with 300-350K miles on them still running great. Told me he read a mechanic's trade publication which listed the Top 10 engines of all time from foreign and domestic manufacturers. 232 V6 was ranked second, right up there with the 22R Toyota engine, which many do not know was actually a hemispherical construction.
MPG is unbelievable for a land whale this size! Average 26 mpg overall, with 30-31 mpg on highway and 22 or so in town. 4-speed auto drops tach way down once overdrive kicks in. I had a Toyota Tercel wagon with a tiny little 88 cu. in. motor (3AC) that only got 28 mpg average due to having auto tranny.
Oil pressure is incredible. 197,000+ miles and it still runs average of 70 lbs. pressure doing 70 mpg on highway and only drops to around 50 pounds at idle.
Not a bit of rust anywhere on body.
Extremely comfortable ride with power-everything and leather interior. Power seats are great. Like sitting in my La-Z-Boy at home!
Has computerized firm ride stabilization, which still works flawlessly.