1989 was the biggest year for Pontiac with respect to press coverage, promotions, and performance. It was not well known at the time, but in 1989, Pontiac produced the quickest and fastest American production car. The "Excitement Division" was also asked to provide a car to pace the 73rd running of the Indianapolis 500; sadly, it would be the final time a Pontiac would ever receive that honor. The Trans Am model was now 20 years old, and it was time for another anniversary edition, with this special 20th Anniversary Trans Am to be based on the existing Trans Am GTA.
Through a unique partnership between Pontiac and an engineering firm called Prototype Automotive Services (PAS), the Trans Am GTA was equipped with a more powerful version of the turbocharged Buick 3.8L V6, originally developed for the Buick Regal Grand National, and the Turbo Trans Am (TTA) became the vehicle Pontiac supplied to pace the Indianapolis 500. Ultimately, 1,555 TTA replicas, rated at 250 hp, were produced for sale, five of those being test cars. But after Car and Driver magazine tested the car, logging a 0–60 mph run in 4.6 seconds, and a standing quarter-mile in 13.4 seconds at 101 mph, they called the 250 hp rating "exceedingly modest," estimating the actual output to be "closer to 300 hp." They also subsequently reported that it was the "quickest 0–60 sprinter available in any US production-car showroom – at any price."
Source: Wikipedia (original)