But if you know your late-edition C4s, you know that a huge change came in the chassis with the RPO F45 Selective Real-Time Dampening suspension system that debuted in 1996, along with the Grand Sport package. Developed by Delphi-the new name for the GM component-parts group that included the former Delco Moraine-Option F45 was intended to replace the existing RPO FX3 Selective Ride Option. F45 sent data from the wheel travel sensors at each corner and the car's Powertrain Control Module (PCM) to a controller that figured out the special shock absorbers' dampening mode to give them the ideal control, doing so about every 10-15 milliseconds. Before that system was ready for production, it had to undergo plenty of in-the-real-world testing, and this blue '95 was the car on which the prototype F45 hardware was installed and rigorously tested, whether on Delphi's computer-controlled laboratory "bump-and-shake" rigs, outdoors at GM's Milford Proving Grounds, or on tracks like Grattan Raceway Park near Grand Rapids, Michigan, as well as the weather-beaten roads and highways of Michigan and Ohio.
One visual cue to this car's Grand Sport test-mule heritage is aft of each door. There, at the top of each rear wheelwell's arch, you can see an add-on flare that extends the bodywork outboard to cover-and thereby made street-legal-the wide wheel/tire combo within. It's very likely that the wider rear quarters that had been used on the '90-'95 ZR-1s were considered, but not used on the Grand Sport out of cost concerns. At that late point in the C4's life cycle, GM wasn't putting any more development dollars into it than absolutely necessary.
Eventually, the F45 system got the green light for production, and this C4's days as a test mule ended. It then became an around-the-plant errand-runner, much like many other test cars before it. In early 2006, Delphi earmarked it for elimination. "They said they had to downsize their inventory," says the National Corvette Museum's Betty Hardison. "They were getting ready to put it in the dumpster." Instead of a date with the dumpster or crusher, this car was donated by Delphi Automotive Systems to the National Corvette Museum, where it's now a part of the Museum's collection of historically significant Vettes. Betty adds that it's still in its as-driven/as-tested condition, with a layer of "patina" that you won't find on other Museum-kept cars. "We don't want to touch it," Betty says, "because that's history sitting there."
Even with the documentation from Delphi and GM, one big hole remains in this C4's history: How many miles are on it? "The odometer was never hooked up," says Betty.
That lack of documented mileage hasn't stopped Corvette lovers from taking a good look at it. Especially during the Museum's Gathering, which was taking place as this story was written. Betty says, "We have it out on display, and the Grand Sport people just eat it up! They can really appreciate the history behind it." Especially if that history is written by the "sands of time" that coat this C4's prototype pieces.