It’s no secret that Jerry Seinfeld is a car enthusiast. In fact, his namesake television show includes numerous nods to his automotive interests: Jerry’s fridge features a Skip Barber Racing School magnet; posters of Porsches line the walls of his apartment; and Kramer, Jerry’s across-the-hall neighbor, drives an experimental 1973 Chevrolet Impala.

Yes, Kramer’s green Impala—the car that famously dons the license plate “ASSMAN” in the Seinfeld episode “The Fusilli Jerry“—is no ordinary Chevy, but one of 1,000 1973 Impalas that General Motors furnished with an experimental front airbag system dubbed the Air Cushion Restraint System (ACRS). How do we know? Well, take a look at the car’s interior in episodes such as “The Race” or “The Pothole” and you’ll spot the telltale signs of an ACRS-equipped Impala: Notably, a four-spoke steering wheel with a pillow-shaped hub that houses the driver-side airbag and a modified Oldsmobile dashboard, which hides the likes of the passenger-side airbag and a driver-side cushioned knee restraint.

While GM refrained from offering ACRS on saleable, regular production order 1973 Impalas, the company sent a number of its ACRS-equipped Impalas to fleet customers throughout the United States for real-world testing. A handful of performance improvements accompany the cars’ trick safety technology, including suspension and chassis upgrades cribbed from the Police Car package (RPO B07) and a 5.7-liter V-8 engine from the Corvette. 

With a minimum of 190 horses under its hood and possibly as much as 250 ponies (a GM spokesperson was unable to confirm if ACRS Impalas used the Corvette’s standard L48 or its available L82 5.7-liter V-8), each ACRS-equipped Impala packs at least 45 extra horses relative to the run-of-the-mill Impala’s standard 145-hp 5.7-liter bent-eight. That’s more than enough grunt to overcome the extra mass the ACRS adds to the experimental Impala’s curb weight.

Despite debuting in the Impala, ACRS never made its way to the bow-tie brand. Instead, GM added the technology to the options menus of certain 1974-1976 Buick, Cadillac, and Oldsmobile models. Low consumer interest toward the feature, however, ultimately led to its demise. The market failure of its ACRS ultimately results in GM abstaining from offering airbags in its cars for more than a decade.

How then, did Kramer’s 1973 Impala go from experimental test car to the ride of choice for television’s favorite hipster doofus? Your guess is as good as ours. We reached out to representatives of Jerry Seinfeld inquiring about the vehicle, but have yet to hear back from the comedian or his spokespeople. That said, it’s likely an enterprise that provides cars to movies and TV shows simply supplied this rare machine to the Seinfeld team. Still, it’s not impossible to imagine Seinfeld himself owning and supplying this Impala to his own show. After all, even a Porsche-fanatic like Seinfeld can surely appreciate the special nature of a rare, Corvette-powered 1973 Impala that also packs one of the industry’s earliest examples of front airbag technology. As Kramer himself might say, “Giddy up!”