XRAY - Model racing cars

I test drove a 2007 RX-8 today which had 167,000km on it. The guy selling it was the 2nd owner of the car and claimed that it was driven most of its life with 87 octane gas. Everything on the car is stock — no modifications whatsoever. The engine definitely didn’t have excellent compression, but I got the impression that it wasn’t bad overall. While driving it I did not hear or feel any knocking coming from the engine (as people claim about using lower octane gas in high compression engines, whether piston or rotary).

Any ideas about this scenario? Is it possible that the 87 octane isn’t so harmful to renesis engines that have reduced compression?