Mmmn. Looks like it's a translated, updated, on-line version of some of the data produced by Fred Kaesmann for his book Weltrekord-fahrzeuge published back in 1984. He's the guy who uncovered the fact that the Russians actually built the first jet car. Mind you, his compatriots had been building rocket cars since the 30's so we were all a bit slow on the uptake.
Robin