Hard to tell from the video on CJ's Miata, but he appears to be drifting up towards the wall as the Aston is passing, but it was probably unintentional and given the lack of downforce there was probably nothing he could have done to avoid the drift. Would be interesting to see the perspective from the other 2 cars. Still full of awesome that the Miata continued on

From Jalopnik:
What happens when you're racing a Mazda MX-5 and you get sandwiched between an Aston Martin and a Porsche 911? Things get very crash-ey.
You're riding on the CJ Wilson Racing MX-5 at Kansas Speedway last week when everything goes a little pear-shaped. Here's what driver Marc Miller says about the wreck.
We got split by GS cars in the closing portion of the race. The Aston Martin was a lap down and not racing for position with 10-minutes remaining. Luckily we were the only car in the 4-car incident to continue - finishing in 10th.
Note: The VW GTI and BMW are both in our class (ST).
Keep your eye on the rear-view mirror to get a sense of the GS cars' closing speeds on the little Mazda. Insane!