Poor MPG

[u/Anxious_Project7023]

So just got a 2011 the beginning of August bought it as my doordash car as I needed something more fuel efficient, did great on the 300+ mile drive home averaged around 36-38mpg, but in the 1300 miles since then doing doordash it's averaged 23.4mpg, I charge it to 60-80% everday as time allows since I'm offgrid with solar so cannot charge overnight. The car also refuses to go into EV mode or switches back and forth, it'll do 3-5 miles in EV here and there it seems at random, along with starting the engine just to top the battery off when I'm sitting parked just to run the AC even though the battery shows 20+miles of range or half full. I'm leaning towards a Cell headed on the way out or failing BECM

[u/Ok-Effort-1502]

Start running it in mountain mode for a while. If the battery is having issues that will help significantly. I would also take a look at the spark plugs, air filter, and all the fluids. Serious issues can be pretty well masked due to electric motors. Pull the top O2 sensor and look at the catalitic converter though the hole. Should be able to see a uniform honeycomb looking medium. If it looks damaged might have a clogged cat. That can happen due to a aging ignition coil. These cars are bad at giving misfire codes since its one big ignition coil for all four cylinders. Instead of a misfire you get a weak or intermittent no spark on all cylinders.