I need to spray paint my engine compartment, rear trunk, and front and rear trunk lids, will the $60 general type spray guns from my local auto parts store work ok. I’m just looking for something that will do an ok job.

It should be fine for engine compartment work. I use one for race bikes. The talent of the painter to manipulate the gun and paint is what's makes a great paint job. The engine compartment is a good place to learn. You could also practice on some spare sheet metal. Spraying too little paint too far away or spraying it on too thick and running is what your trying to avoid. Good luck!