Bridging the gap between battery electric vehicles and gasoline-electric hybrids we find cars like the 2012 Toyota Prius Plug-In and the 2012 Chevrolet Volt.

Both are essentially hybrid vehicles, but use the technology in different ways to achieve different aims.

Ultimately though, which vehicle costs less to run? Ray Iannuzzelli at has saved us all the leg-work by calculating the cost per mile of each vehicle--and the sort of journeys over which each car would be preferable.

Ray used EPA data wherever available to work out the cost per mile of each vehicle. This meant considering the electric range of each vehicle--an average range of 42 miles on electric power in the Volt, and 13 miles in the plug-in Prius. It also considered the mileage figures, giving the Volt combined mileage of 37mpg and the Prius, 50mpg, both on gasoline alone.

Dollars per mile

The first graph is perhaps most interesting, illustrating the range over which each car benefits.

The Volt has a clear advantage up to 65 miles, but this doesn't tell the whole story. The Prius actually shows an advantage below 16 miles, which Ray suspects is down to its brief electric range, but also being more efficient on electricity alone thanks to its lower weight--the plug-in Prius uses only 0.29 kw-hr/mile compared to the Volt's 0.36 kw-hr/mile.

Between 16 and 65 miles, the Volt would cost less to run, owing to the greater EV range, the Prius unavoidably having to use gasoline here.

That's an important consideration if you have a regular commute of that sort of distance. As many Volt owners have found in the real world, they can go months without adding a drop of gasoline, only needing to pay for the car's electricity usage instead.

Beyond 65 miles, the Prius' excellent fuel consumption figures draw it back into contention, past which point it becomes the cheaper--and cleaner--car to run.

All figures have been based on gas prices of $3.79 per gallon, premium gas (for the Volt) at $4 per gallon, and an average electricity rate of $0.12 per kilowatt-hour.

Ray also points out that as gas prices rise, the $/mile figure would approach 75 miles, as trips in the Prius become more expensive sooner. Of course, past this point the Prius's advantage would stretch further, as it uses less gas over longer distances.

The results aren't unexpected, but knowing the figures could certainly help buyers choose the right vehicle for their needs, a situation that isn't always clear from the bare EPA figures.

You can find the full figures and graphs in Ray's post on

Looking at the figures, which vehicle would suit your own needs best? Let us know in the comments section below.


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