I'll take iRacing any time over pCars, pCars has some great arcade qualities to it, including wacky scaling and physics . Not here to start a war on which service is better because it's really a no brainer. I do own both, one is a game the other a racing service. iRacing's graphics are improving constantly and they have put their resources to much better use then pCars IMO.
Every once in a while I fire up pCars and race the computer, but for more of a real experience iRacing wins hands down.