I was wondering if it would be possible to rather easily hack a car's cruise control into adaptive cruise control using a cheap radar gun and possibly a simple logic board. Adaptive cruise control is a new option on cars that runs about $1200 and up. After you set it to your desired speed it automatically slows your car down to speed of the car in front of it, and speeds it back up to your set speed if he goes faster.

I was thinking if you bought a police quality radar gun on e-bay (these run for like $75), and mounted it into your grill, then somehow interfaced it with the simple accel/decel switch on your steering wheel (or possibly the cars computer) if you could accomplish the same thing for a couple hundred bucks.

Has anybody done this? I'd really like to see someone take a stab at it.

That could be done for sure. However that would involve interfering with car's onboard computer, which is basicly different in each model. The other thing is that it uses a distance parameter instead of speed of the car in front. Calculations are more stable this way.

The problem is that your safety is involved here, so I'm not sure it is worth the effort.