Chervrolet Volt 2016 - what if...

It's not a lie, it's just one way of characterizing the use of gasoline by drivers based on some set of assumptions about their driving patterns between charging.

I was having a little fun with my reply... Sure, the NEDC number being quoted by Vauxhall is UK gallons. If you convert it to US gallons it is 196 mpg.

On the other hand, that's an old estimate which GM hasn't bothered to update even though the Volt now has an extra 1.25-1.50 kWh of usable capacity in the battery pack and that initial EV range heavily influences the final composite mpg number. I don't remember all of the details around the calculation, but a back of the envelope approximation implies that an updated estimate would likely be 300+ mpg (US). GM is really being overly conservative.

Basically, that estimate assumes you drive a particular NEDC test cycle a certain distance (somewhere around 62 miles, I think, so maybe it is 100 km) and you are allowed to fully discharge your plugin battery before burning gas. The Volt/Ampera used to have a NEDC range of 83 km or about 51-52 miles and an estimated 47 mpg (US) on gasoline only. Of course, the first few miles on gas are less efficient with a cold engine.

For example, for a 2011-2012 Volt/Ampera drive 51 miles on battery and then another 11 miles on gas at about 35 mpg on a cold engine and you drive 62 miles on .315 gallons or about 192 mpg.

Now, update the EV range to 57 miles plus another 5 miles on gasoline on a cold engine at 25 mpg and you drive 62 miles on 0.20 gallons of gas or about 310 mpg.