It's important to remember that the gas engine and the electric motor are integrated... they're attached to one another so if one is turning, so is the other. When you're in all electric "mode" it simply means that the engines valves have been modified (shut off) and fuel is shut off. The pistons and all are still going up and down, because they're attached to the crankshaft which is part of the motor. SOooooo... this means you won't hear or feel anything dramatically different. It's all very subtle.

I've had my '06 HCH for two weeks. I'm getting better at being able to control going into electric mode, but it's still quite difficult to do. The easiest way I've found is to be going about 45 on level or downgrade with NO traffic anywhere near you. Take your foot completely off the gas for two seconds. The MPG gauge will go up to full bars. Then apply just a tiny bit of pressure to the accelerator pedal to make all the green bars go away from the charge meter. If you give it just enough, you'll get one or two white bars on the "assist" side of the meter... but the MPG gauge will still show full. Once you're in this mode, you can play around with the pedal a little to vary the assist from one to four bars. If you goof by either jabbing the accelerator too much or letting off of it too much, it will take it out of full electric "mode" and you'll feel a slight surge (which is the engine applying power again).

Just play with it and it will happen! Just remember to try this with no traffic around you!

By the way, I've been able to enter this mode as low as 10 miles per hour, and as high as 65. I can always do it for just a second... but the trick is keeping it in there! The longest I've gone is perhaps 20 seconds... but that's because traffic prevented me from continuing!