Which Sears Auto Race do you have? (There's two, one where the track is horizontal, and the other one has a vertical track like Mattel)
http://www.handheldmuseum.com/Sears/AutoRace.htm

I don't think Sears ever licensed from Mattel. I know the horizontal one is a licensed game from Tiger (Tiger Raceway, their clone of Mattel's game).

The vertical one appears to be licensed from Dynamic Toys (I think they are the maker)-
http://www.handheldmuseum.com/Misc/DynamicToysDynamicRace.htm

There's a couple knock-off versions of the vertical format that got licensed all over the world it seems...

I have both of the Sears games, if I can find them I'll take a peek inside and see if they are the same chips or not.