[egmacrae]

Usually when I am in EV mode on my PHEV, the drive information mpg is 999.9 until I've used up my 26 electric miles. Lately it has been showing me 50-90 mpg when I still have juice in the battery. Did i accidentally change a setting or has something gone wrong.

 

[brandent]

That means the gas engine kicked on at some point either by
a) you accelerated hard (anything over about half throttle).
b) it's fall and getting cool. in EV mode the engine will turn on if heat is called for. It will run the engine steady at about 2000 rpm until the coolant is hot then shut off. During that time the engine charges the battery so it is in fact using the most efficient possible gas burn.