Hybrid cars beat both conventional and coal-powered electric ones in terms of total energy consumption; that includes what’s required to manufacture the car, what’s used to produce, refine, and transport the fuel for it, as well as the energy consumed driving.

The fact that hybrids beat out conventional gas-guzzlers is no surprise. The energy it takes to make a hybrid car is about the same as the amount that produces a conventional car; each car results in roughly 6,600 pounds of greenhouse gases getting spewed into the air. However, hybrids are nearly twice as fuel efficient. So hybrid vehicles are responsible for only a fraction of the emissions per mile as those generated by their conventional counterparts.

Here’s how the hybrid stacks-up against the electric car: The manufacturing energy invested in an electric vehicle is about double the amount required to make either of the other two cars because of the hefty battery. The process in total pumps out 13,000 pounds of emissions. And although it’s true that electric vehicles produce almost no pollution while tooling down the road, the source of the power can spew a fair amount of pollution.

According to EPA estimates, the typical coal-fired power plant produces an average of 2.1 pounds of greenhouse gases per kWh.

If we assume the fuel-efficiency of an electric car to be 2.4 miles per kWh, the estimated emissions-efficiency of an electric vehicle that derives its electricity from a coal-fired power plant is about 0.87 pounds per mile.

Over the course of each vehicle’s lifetime—assuming 100,000 miles driven per vehicle—the hybrid would be responsible for about 60,000 pounds of emissions, a conventional "economy" car would claim around 91,000 pounds of emissions, and the electric "coal-powered" vehicle would take on 100,000 pounds of emissions.

Even if the average economy car achieved fewer than 28 mpg or the average electric vehicle was able to squeeze another mile out of each kWh, the seriousness of the pollution problems caused by burning coal—even beyond those associated with greenhouse gases—would likely still make the coal-powered electric car the least eco-friendly of the trio.

On the other hand, if the electricity used to power the electric car is generated by a hydro, wind, geothermal, or solar power plant, total greenhouse gas emissions will be little more than those emitted during the car’s production. When these relatively cleaner forms of electricity are used, electric cars are the most eco-friendly vehicles.