Yeah, I'm pretty sure the inverted geometry technique is the same perspective as a reflection. As Matty says you wouldn't see the underneath of the car with this technique either, since the normal geometry would obscure the underneath car in the reflected geometry. The exception here being a low view height where you would see the underneath of the car in the reflected geometry, but you would in a true reflect as well. The main issue is lighting really, as with a light source above, the top of the car would be bright and the underneath dark, but the reverse would be true on the inverted geometry.
If you draw yourself a little picture with a shape above a line and a shape below it and a spot for the observer, you can demonstrate this to yourself. Draw a line to the surface and through to the inverted geometry, plus a reflected line back up to the geometry. Assuming you have a steady hand and have drawn your scene accurately, the line will touch the same place on the geometry of the normal and inverted object. You'll also see the underneath of the inverted geometry is obscured by the normal geometry when you try and draw lines from the observer to it.
Edit: this is only true for 3d scenes btw, not for 2d
