The University of California at Davis has a Plug-in Hybrid and Electrical Vehicle Research Center. They recently developed a online tool EV Explorer that helps you determine the annual energy costs of different vehicles. The user can compare up to 4 different vehicles (including ICE, electric and hybrid) simultaneously. The researchers use the MPG data from the federal government, Google Map data and current gas and electricity rates.

The initial version allows you to enter in some factors such as

Your home location Your work location Access to charging at work Exact price of electricity at home

For example, I put in the commute of a friend of mine who daily drives 111 miles from Tracy to Mountain View. I selected the Tesla Model S, a Toyota Prius Plug-in, a Toyota Prius c and a Chevy Volt. At today’s low gas prices, both Toyota Priuses cost a little less per year in energy costs vs. the Model S but the Volt was over $300 per year more.

With the current version of the tool, you can change the price of energy. I modified the gas price to $4.00 per gallon, which reflects the pricing we had for several years. With this scenario, the Model S would be up to $1,000 less in energy costs for her commute than the Chevy Volt.

If she put added solar onto her house, used free workplace charging or relied solely on superchargers, the Model S could be driven with zero energy costs.

In the end my friend bought a new Toyota Prius c for her commute. The C version is smaller than the typical Prius and costs $10,450 less than the Prius Plug-in. Her estimated mpg is 53/46 mpg. She made a good choice considering her current situation. I would not want to drive that far on any regular basis in commute traffic – even in a Model S.

Although the tool today only considers annual energy costs and not other factors such as insurance, maintenance or initial car cost, UC Davis is continuing to develop the tool.