Actually zero cars have a serious mechanical purpose to them. With B&M Trains, each car trails the one after it like a trailer behind a car via a universal joint. Without the zero car, there is nothing for the front car to hang onto & wouldn't work. The zero car is fixed to the front car via an inline axial pivot only - no more 'trailering' effect here. If you look at photos of B&M Trains carefully, you'll notice the zero car & the front car never pivot towards each other in inversions. With Inverted coasters, the front car is a zero car with seats attached to it! Exactly the same goes for Floorless coasters. If you ride in the 2nd row, you'll see the seats in front of ya never tilt towards your face in inversions & the likes. Alpengeist has a true zero car to reduce the stress on the axial pivot & to allow more speed. I know this as built a model B&M Inverted & was confused as to how the front car runs without anything to hang onto. Studied a photo of a train on Raptor's Loop & noticed the front two rows were still parallel to each other, 'Eureka!' 
 
Vekoma SLC trains are exactly the same, only in reverse. The zero car is at the back! 
 
 *** This post was edited by CoasterGod on 4/18/2001. ***