Do these spoilers help with handling, or wind resistance, or gas milage.

Or all three, just wondering....

They will definitely help the natural front end lift these cars experience above 70mph.

The 69 Camaro front spoiler puts down about 75 lbs of force at 85mph compared to no spoilers at all: http://www.yearone.com/enthusiast/restoarchives/winter99/18-21camaro.pdf

This Cuda Trans Am spoiler is a lot MORE effective because it is closer to the ground and wider.

They should also help with engine cooling. This is because the air behind the spoiler is blocked and slowed down creating lower pressure under the engine compartment. That will draw more hot air out of engine compartment and out under the car.