Mike - Yep, that's the other article I mentioned. It was published originally in Hot Rod, but I also saw it show up in another publication some years later. I don't think I have my original any longer, but you got the details right there.

Look at those pics from Cecil County in that article: everybody is wearing jackets and the trees haven't got any leaves on them. It was still late winter or really early spring when they ran that test and I'm guessing the air was killer that day.

That same car was tested later that year by some other long-forgotten car magazine and they were nowhere near the MPH the SS&DI crew saw on that day at CC. The other tests were done at Suffolk Raceway in SE Virginia, which was also right on the coast and had a number of records set there. But if the SS&DI test was Feb / March and the other magazine was in the summer, that's a major difference in atmospheric conditions.