Here is an interesting, um, feature of the car: The car has a range display that shows gas range + electric range (when everything is full it will display something like 600 + 22 or so). The trip meter, on the other hand, will show you total miles, and “EV Miles”.

The way these are calculated is very interesting: The gas range value shows “hybrid range available” and “EV only” range available. The trip meter, however, shows total miles and “EV miles”. The “EV only” range is not the same as “EV miles” on the trip meter.

I seem to be averaging about 1000 miles a tank of gas, at least that is what the trip meter is telling me: ~1000 miles total, and 700 miles EV. Hang on doesn’t that mean I only went 300 miles on gas? Nope, this is where the strange math comes in. The “EV miles” on the trip meter simply measures how many miles the car traveled on battery power only. Now you can see the disparity: When running in hybrid mode the car will run the engine at its most optimum speed and store excess rotational energy in the battery (e.g. runs the engine faster than required to move the car and uses the generator to take up the excess speed above what the car needs to move). When the battery has stored sufficient electricity it uses the electric motor to drive the car and shuts down the gas engine (until the battery is depleted below a certain point). In this electric drive state the trip meter counts the distance as “EV only” because the gas engine is off, but the range meter counts this towards the gas engine range (presumably because the electricity came from the gas engine).

The net effect of all that is there is no way you can relate the range values to the values the trip meter shows you. Sure the range is a pretty accurate representation of how far you can go on your remaining fuel but there is no way to account for the differences between the trip meter and the range value.

Yeah I know: “This seems like a long blog post to be nit picking about some gauge values” and you’re right but I have to post about something now and then LOL. I really count this difference (and post here) as just an observation and not “nit picking” though as it doesn’t bother me that much: You are going to use the range and the trip meter for two different purposes and probably never will want to “do the math” to see how they relate anyway. All these different ways of calculating, though, really make it difficult to come up with a “true” mpg figure for the car though (it does show one in diagnostic mode but that is for another post).