The 928 was only sold as a 2 door coupe. It was probably supposed to replace the famed 911 line, but it seems that many buyers just couldn't adjust to the styling of the 928. Many collectors still contend that the 911 was the better sports car and more deserving of being called the flagship model from Porsche. That said, the 928 was a very high performance vehicle that could match just about anything on the road of the day, and with similar drivers the 928 would have no trouble beating the 911 in any race I can imagine.
The top speed on the 928 was higher than any other production car at the time. It also had more predictable handling, making it easier to drive for drivers who don't have racing experience.
Through the early 1980's, the Porsche 928 had front and rear spoilers on the S models. Another variation on the 928 was the 928 GTS. It had much wider rear wheels, and a wider rear fender to help them fit on this car and not stick out the sides. CS, SE, GT, and Club Sport were some of the other trim options on these cars.
If you are interested in buying a Porsche 928 or any of its variations, the easiest place to find one for sale is on eBay. I'm sure there are at least 3 of these cars up for auction on eBay right now, along with lots of original and compatible parts listings.