I'm sure they are better experts on toxicology than I am, I f uck ing hope so. But last time I checked, you could smoke marijuana up to six months previous and still test positive. You knew that right? But I'm pretty sure that if you run a toxicology within 24 hours or 124 hours on a corpse, the results are not going to be too different. That body's organs aren't processing anything anymore except maybe on THE WALKING DEAD.
But I'd dare say your ability to drive a race car today would not be very much affected by you smoking a joint back at spring break. Of course, you are probably not going to win often if that is your game plan. Getting out of the car ANYWHERE there are other moving cars isn't the smartest thing to do unless of course your junk is on fire.