I visited this forum a while back and got some ideas here about what might be causing false laser alerts on my 8500 x50. I drive a Subaru STi. I've had great luck with my 8500, but sometimes it gets into a string of false laser alerts coinciding with hard acceleration.
One poster's theory was voltage spikes. I switched my unit to V mode and found my voltage to be over 14 volts probably 75% of the time. The voltage doesn't really fluctuate much. I decided to go with another theory that it was caused by stray RF in the car's circuitry. Here's my fix:
I use the smart cord, which plugs into the unit with the RJ11 phone jack. I obtained the following from Radio Shack for about 6 bucks: 1 6" 4-conductor phone cord w/ male RJ11 on each end (I call this a patch cord because it's so short). 1 female/female RJ11 coupler. Then from an old computer monitor clip the RF filter thingy out of the power cord. It's the component near one end or the other of the cord about the size of a small battery. Leave a couple inches of wire to work with.
Take the 6" patch cord and slit the sheath open in the middle for about 3 or 4 inches. Take out the green and red wires and cut them in the middle. Bare the wires on the patch cord and the RF filter. NOTE: on my smart cord, the wire colors were exactly the opposite of the phone cord, so I connected the + lead on the filter to the green wires on the patch cord, because + on the detector/smart cord is the red. This keeps it correct all the way through, even though the + is now green on your patch cord. So anyway, be sure to attach the + and "-" to the correct wires in the patch cord. Connect everything so it's road-worthy using electronic solder. Insulate with tape or whatever. Attach the f/f RJ11 coupler on the end. Secure the whole thing with some electrical tape and dress it up so it looks nice.
Now you can plug the smart cord into your new filter assembly and plug the filter assembly into the detector. This way, you can use it or not, or use it with other units, and you don't have to destroy a smart cord to do it.
I have spent considerable time trying to get a false laser alert after installing this thing. Nothing yet, and all else seems to function fine. I can't be sure it has actually done the job, only that I haven't had a false alert since installing it. Just to try to be somewhat scientific about it, I did leave it off the unit at first until I got my first false alert, then clicked it in while driving, and then got no more false alerts. Anyway, it's so cheap, if it doesn't work for you, you can throw this thing away and not feel too bad about it, then spend the 80 bucks with Escort to get the falsies fixed. Since you haven't changed anything on the unit, no one will know you've been experimenting. Another Note: I'm not an electronics guy, so do this at your own risk (though I don't think it's very risky).
Incidently, I used to test my laser detection by shooting the detector with a laser rangefinder (like those used for hunting/shooting). It sets it off just fine. I haven't done this yet this time because the range finder is dead right now. It's a good way to test it though, I think it's basically the same technology.