why not ?
I've done both.

it's not cost effective to run r/c car fuel in .40 size model. But If you have an extra gallon you want to
use. why not ... It's over $30 for a gallon of 20% traxxas.
Burned a half of gallon in my raptor.

I've ran gallons and gallons of 15% aircraft in my savage, tmaxx or rc10
It'll smoke more ..that's for sure
It'll run hotter, so I had to richen it up.
It didn't have the power of the 20%.

I've even mixed it becuase the hoobie shop was closed on sunday.