A friend inherited a Mercedes that had been sitting in the woods for 2 years. When we pulled up the carpet there was about 10,000 big black ants. 2 bug bombs tossed in the car with the windows up and doors closed did the trick. Then lots of vacuuming. Gross but it works! I think you’d be fine to set one off in the engine bay. Take off the air filter, find where the bug bomb will fit, set it off and close the hood.