If they DID have a machine like that (and I really doubt they do, your mom is just trying to put the fear of god in you), it would probably have a trigger set at 65 mph... because I don't think any state other than Montana, Wyoming, etc. has a speed limit about 65. If the idea is to keep you at or below the speed limit at all times, setting it at 65 would make sense.

Teg711, I've also heard about those machines you have to breathe into to start the car. Man, that sucks, even though it has a good purpose. How embarassing, though, if you failed it; I bet it records entries, too. The cop will pull out the disk, and it will read "attempted DUI, car didn't start," and the dude would be in a world of trouble.