Since i've owned this car i have done routine maintenance. i have had no problems with reliability. i have over 180,000 miles on the car, the 3.8L supercharged motor runs strong and gets great gas mileage. 32+mpg highway and in the city with traffic i can still get 23/25mpg. its a full size car that fits 6 people with every option.
The electronics will go out on you and expect to pay a few hundred to fix (rear defrost, seat adjuster). As everyone says, 30+ mpg highway (I once averaged over 38 on a 150 mile trip!) but in the city it's a dog, I'll get anywhere from 13-21 in the city. I think it looks great, and the sound system is amazing. Buy it if you want to be spoiled without burning a hole in your wallet.
I bought my Park Ave used with 40K miles. This car is by far the best full size car I have ever owned. It is reliable as it is comfortable. In the past 60K miles, I have not had to replace anything major on the car. The 3.8 L engine is easy on gas and provides adequate power in typical driving conditions. The only negative I have experienced with the car is that the front brakes require above average maintenance. Overall, a small price to pay. The trunk space exceeds the available storage of a Pathfinder or Explorer (with the second row seat up). This is the vehicle of choice for my family vacations. My young son fittingly calls our Park Ave "The Comfy Car".
I purchased my second 1999 Park Ave after trading in my first 99 for a 2004 Grand Prix. While the Grand Prix is sporty, it doesn't hold a candle to the size, ride, mpg and trouble free driving I have experienced with the Park Avenue. I routinely get over 30 mpg on the highway and over 20 mpg in the city, that is better than my 4 cylinder pick up truck! I purchase my current Buick with 57,000 miles on it and now have over 112,000 and have only had to perform routine maintenance on the vehicle. It is a comfortable, reliable ride that I never get tired of. I also have a 2007 Lucerne, but as nice as it is, I prefer my Park Ave and will replace it with another when the time comes.
I've had this car for a week now with 123,227 miles on it and i'm in love with it. The ride is better that most european cars i've had before. I'm a sales man so i drive arround a lot and this car makes me enjoy the road more each time i drive it. It's very good on the gas too and fits all my family comfortably. All it needs is a good paint job and it will look like new!!!