cringely

As far as lasers, I heard that law enforcement tries to aim at the license plate. The standard CA license plate is white with reflective paint (which makes detection easier and at longer distances). If your license plate has a reflective surface, one passive countermeasure would be to paint the reflective fields with a flat finish of the same color. I don't know if anyone makes a clear coat that absorbed in the IR (infrared) bands, but that could be another solution. One way to check (in the visible wavelengths) is to shine a flashlight at the front of your car at night and see what reflects.

Iceter

It's my understanding that cops aim laser at flat portions of cars (like license plates) because the beam is very narrow and they get a much better return signal at the device when they do so--especially on off-axis shots. This isn't necessary with radar because the radar wave is very wide and a radar gun can pick up the return signal at almost any angle.

I don't know if it's possible to absorb a laser shot and prevent all of the signal from bouncing back from the target.

it's also not practical to design a car to be radar avoidant and I'd be very surprised if Chevrolet engineers put any thought into making Corvettes less susceptible to radar. I know from reading "All Corvettes are Red" that the engineers would gladly make the radiators more upright and larger if they could. They used to be at an angle for no other reason than that the nose is low.

Finally, radar doesn't need a flat target to receive a good return signal. Any part of the car that is perpendicular to the beam will return a signal--even a sharp crease in the bodywork.