Wow. The degree of misinformation in that post is staggering. The only thing even resembling a fact is the relationship to rFactor.

The Simfactory developed ARCA on ISI's rFactor engine. They did this not only with ISI's knowledge, but their blessing (and a license).

ARCA Sim Racing is based on Image Space Incorporated's game engine, gmotor2, which was used in rFactor. In August 2006, The Sim Factory purchased the rights to use the gmotor2 engine in their software[1], and with the help of ISI, The Sim Factory was able to recode the engine to produce a realistic stock car simulation.

ARCA Sim is superior to rFactor's stock physics. Why? Because the Sim Factory actually worked in direct cooperation with ARCA in developing the sim. They have data from teams, engineers, and the tire manufacture, Hoosier.

The only sim to be regarded as superior to ARCA for stock cars (and this is arguable depending on which camp you're in), is iRacing. Dale Jr is known to run both sims frequently. He is an avid sim fan, and even participated in the development of iRacing. I cannot confirm if he was involved with ARCA Sim, but he has certainly been a strong supporter of it. And he's just the most visible and vocal supporter. There are several drivers who sim race and use ARCA.

So. Which part of that is inferior to rFactor? Oh, right, The design is totally ripped off.

If you want a versatile sim, rFactor is the ideal title. It's intent was to be an open sandbox for modding. You simply cannot get more variety than with rFactor. But for a dedicated stock car sim, ARCA is alone, on the top with iRacing.

EDIT: Just realized I argued with a 14yo.