1998 Pontiac Grand Prix GTP review from North America

The transmission failed at 50,000 miles. I thought I had somehow caused the problem because I had replaced the ATF with Mobil 1 synthetic at about 5,000 miles and then again at about 45,000 miles. Although I was very careful about keeping everything clean, I thought maybe a piece of crud had gotten into the shifting modules. So anyway, I had the transmission rebuilt by the Pontiac dealer where I bought the car. It worked great until about a year ago (mileage unknown). When I pressed hard on the accelerator at about 50mph, the transmission would not immediately drop out of D into 3rd. Instead, the engine rpm would pulsate violently. However, the car could be accelerated slowly without any problem. I took the car back to the dealer and they told me that the plug wires were bad and also that one plug had failed. They also replaced a fuel filter. I'm not sure what they "actually" did to fix the problem because I had just had the plugs replaced a few thousand miles prior to that. The car has begun doing something similar since 100,000 miles in that it hesitates and pulses slightly when shifting from Drive to 3rd under acceleration.

My current problem is a noisy supercharger drive belt tensioner. I have replaced it twice with aftermarket tensioners from Auto Zone and it still makes a racket at idle (in Drive). At the slightest increase in RPM, the noise goes away. After reading some of the comments made by others, I'm beginning to suspect the supercharger drive coupler. Any ideas?

The car is still very quick even at 105,000 miles and gets great gas mileage. About 23 around town and 34 on the Interstate.

I wish the seats were more comfortable on long trips.

I can't say that I am happy with any GM dealer repair. If you aren't VERY knowledgable (I'm not) about the newer computer controlled cars, you are at the mercy of the dealer repair shop.