The transition is something that takes practice, try to launch with as little load as possible(without people behind you honking!), the smoother you accelerate the smoother the transition.

The reason the MPG bar goes to zero at a stop is because you are not traveling any distance so it cannot calculate the MPG. When you are in EV mode your MPG is actually infinate but is calculated depending on how many miles you have driven since resetting the FE meter.

Try this, fill up your tank & reset the FE trip meter then switch to the digital readout of accumulated MPG (digital) instead of the bar gauge(MPG) which is a real time readout.

Make sure you are on a flat road and stay in EV as long as you can and watch the readout. You will see that we actually own a perpetual motion machine!!!!