You step on the brakes. Try your Control Roll: roll 1 die. If the result is less than or equal to the sum of your Driving skill and your car's Handling Class, you made it.
If you make your roll, you hit the hay without damage and stop.
If you miss your roll, you are too slow hitting your brakes. You slam into the bales at a good 40 mph. Your car takes 2 hits of damage. Mark this damage off on your Record Sheet.
You drop into first gear and push the hay out of the way. Turn to 338.