I have 2600 miles on my 2012 mdl II. A month old. I have been averaging 47.5mpg since day one based on miles driven and gas put back in tank at each fill up. I have used only Mobil bottom 87 oct gas.Last fill up got me 48.2, very nice, then I filled up with mid grade 89 oct as it was all I could get then. The next day I was in the dealer for my 1000 mile checkup. when I got out my battery was down to 25%, okay no biggie. Then from there on out I notice my mpg changed alot. The comps used to read 49.1-50.1. Now it reads 42.2-44.1. I drive the same way and my 85 mile round trip to work hasnt changed. My first fill up since the dealer, got me 45.0 mpg. wow a big drop off. Now then, did the dealer change some setting or did the change in gas from 87 to 89 oct gas cause the decrease?
Did they add oil? Too much engine oil is not good for mileage. You may wish to check to see if it is over the 'full' line'. Did they adjust the Tire Pressure? You want at least 38F/35R Other than that, weather, tire pressure, traffic, and slope all change your mileage. Your Mileage May Vary.
I have aired my tires up to the 40s...only to have the dealer let about 10psi out during service. maybe that's it.
With the SOC so low, they probably left it sitting, On, for a period of time running down the battery and having it idle.
