Earthquake,
Well, unless you have one really, really, powerful and heavy stereo system, or something such as bulletproof glass or armor plate was added before you got the vehicle, I'd suspect that the scale is off or that therewas residue on the scale.
Sometimes the scales at places such as rock quarries or even bone yards aren't zeroed or have a lot of residue sitting on the scales, which is why when they give a weight for vehicles coming in and a weight when they come out and bill or pay for the difference in weight, it doesn't matter that much, as the weight of residue is fairly constant. Plus if you're off by a couple of hundred pounds on a 20+ ton load, it's not that significant.
On the other hand, if that scale really IS off by that much, that's where I'd favor going if I had something to sell, that was being sold by the pound.
(The wrestler sharing your screen name is probably before your time, and probably weighed over 400#, so if HE was sitting in the car or standing on the scale when it was weighed.....)