Technically speaking, this button shouldnt be very hard to implement at all. If we could somehow get the software code for the FEH/MMH, this would be a easy to do: so instead of turning the ICE off when braking/L, the software would turn the ice off when braking/L/button.

I would add to the wish list a button for turning off the ICE completely, like some cars in Europe do. I like to know how fast can an FEH/MMH goes on level road on motor only without the software kicking in the ice ~35mph (so far I can only get to ~31mph without ice on my 07 MMH - very very slow acceleration).