If you want to drive the absolute cleanest car possible – and if you’re reading this site, we’re willing to wager that you do – then you need to calculate the total well-to-wheels energy use of the car and everything you put into its tank or battery.

When it comes to comparing types of vehicles – hydrogen, standard gasoline and diesel, or battery electric – then a full accounting of the averages reveals that electric cars are the total efficiency winners.

At least, they are in a new study from the UK-based Transport & Environment.

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The results are not even close.

Starting with all renewable energy for either charging or to process the gasoline or hydrogen, all-electric vehicles managing an overall efficiency rating of 73 percent, compared to 22 percent for hydrogen fuel cell vehicles, and just 13 percent for standard fossil fuel vehicles using gasoline made with the Fischer Tropsch process.

Of course, there are many details that need to be picked apart here.

For example, T&E says that fossil fuel vehicles lose 70 percent of the energy in their sloshing tanks because of inefficient engines.

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That may be a good average, but Toyota made a big point of saying that its latest Prius has a 40 percent thermal efficiency, which means 60 percent energy loss, not 70 percent.

Also, the efficiency rate at which an EV charges also plays a big role in the well-to-wheels efficiency.

Lastly, given T&E’s location, we assume it is basing the numbers in the study on the European electric grid and European MPG figures. Oddly, we can’t find the original T&E report to confirm this guess, but if you do, please let is know in the comments.

UK's Transport & Environment says that electric cars are the most efficient

UK's Transport & Environment says that electric cars are the most efficient

Of course, any study like this is not necessarily applicable to your personal situation.

As we discussed when we looked at similar comparisons of EVs and hybrids in the U.S., there are a lot of regional differences – to say nothing of the variations in your specific vehicle.

Given all those minor and major variables, in some rare cases (i.e., for three percent of U.S. drivers), driving an electric vehicle is not the most efficient option.

Even so, when you look at the averages, you’re most likely going to be better off plugging in than gassing up. If anyone says otherwise, ask them to show you the math.


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