Best option out there is:
Rush Rally 2 - 0.99 dollar - last updated May '17 - no in-app, multiplayer option - see also review
here.
A few race apps with multiplayer, 64bit. As far as in-app purchases it's indeed difficult to find an app that doesn't have any and which is recently updated unfortunately.
Here are a few I could find. I love the Reckless Racing games but they do have in-app purchases aside of pay once but I never bought the in-app purchases though.
Reckless Racing 2 - 1,99 dollar - last updated Dec. 15 but does support 64bit, but has a few in-app purchase which you don't need to play the game
Reckless Racing 3 - 3,49 dollar - last updated Nov. '16, has a few in-app purchases which you don't need to play the game
Another option for you is to look at
this TouchArcade > paid > racing > this year update list of apps.
Horizon Chase - free, 2.99 in-app to unlock full game - last updated Sept. '16 - seems to have multiplayer option but please check though. They call it 'beat your friends records' so it might not be a live race then.
F1 2016 - 4.99 dollar - last updated Dec'16 - no in-app, not sure though about multiplayer. please check see also
this review from MacStories.
Grand Theft Auto: San Andreas - 6.99 dollar - last updated May '17 with 64 bit support, no in-app, not sure though about multiplayer please check. The game is as you probably know not a typical racing game though.