Trip to San Francisco this evening for some hoped-for but unrealized sunset photography, dinner, and a friend’s wedding celebration. Simplified my life and just left the car in Normal Mode the entire trip, instead of switching to Mountain Mode (lousy excuse for Hold Mode—hold the battery right where it is, please—but all that’s available in the US Volt; the idea is to reserve some charge in the battery for the in-town stop-and-go city driving, where an ICE [internal combustion engine] tends to be at its least efficient). 79 miles round-trip, including I-280 to Brotherhood Way, pushing the speed a bit, rather than the flatter, more sedate, and more efficient US-101. (But, I-280 is a much prettier drive!) Battery was fully drained before reaching the City.
Got 37 miles on the battery, 42 on the ICE; burned just over a gallon of gasoline. Counting only the gas, that’s 75 mpg for the round-trip, and 40 mpg for the ICE-only portion. Energy consumed: about 10.5 kWh off the battery (it takes about 11.9 kWh to charge the battery using the 240V charging system, 12.2 kWh using the 120V charger), 138 kWh from the gasoline via the ICE to drive the generator, yielding a total energy consumption of about 150 kWh.
Getting a little more precise yields an MPGe of 69.3 if you include the charging inefficiencies, 70.0 if you exclude those. MPGe is “miles per gallon equivalent”: convert the energy used from the battery into the equivalent amount of gasoline, using the following conversion factors:
- 1 kWh = 3.6 MJ (megajoules).
- 1 liter of automotive gasoline yields 34.8 MJ of energy; 1 gallon, therefore, has 131.7 MJ, or 36.59 kWh.
- The Volt’s battery provides 10.4 kWh (the battery actually has much more energy than this: 16 kWh; the on-board battery management system limits a full charge and the depletion level to improve battery longevity).
- A 240V EVSE (“electric vehicle service equipment,” the industry’s technical term for a “charging station” or “charger,” since the actual charger is in the car itself) runs at about 87.5% efficiency (based on energy used from the grid and energy stored in the battery). A 120V EVSE runs at about 85.5% efficiency. These numbers are based on follow Volt owners’ actual, measured consumption: I don’t have the ability to get these numbers from my installation.