Loory, I wouldn't bother with a fuel warmer on the Vibe. The fuel rail is really tucked in close to the engine and already gets quite warm I'm sure as there is an engine cover (plastic thing you see when you pop the hood) that has insulation on the backside of it. I'm sure the fuel rail stays nice and warm once the engine is up to temperature. Here is a picture that shows how close the fuel rail is to the head. As you can see, the bottom side is surrounded by the intake manifold. In the second picture (not my engine) you can see that the engine cover goes completely over the top of the fuel rail and pretty much touches the intake manifold where you see the step in the intake manifold. It really seals in that area. The boys at Toyota are a smart bunch.
When I pulse and glide in the Matrix I always use engine on and I shift to neutral 95% of the time. On rare occasion going up a steep hill I won't take it out of gear because I know I need to pulse again soon.