When judging a car's "green"-ness, sometimes fuel economy isn't the whole story.

The new website RideNerd lets car owners and shoppers compare the overall environmental impact of different cars, from the efficiency of their manufacturing processes to their EPA greenhouse-gas scores.

The site allows users to compare two cars--starting with the 2013 model year--on the basis of several such metrics, and assigns an overall score to each vehicle.

RideNerd rates cars based on four criteria: Affordability, Fuel Economy, Air Quality, and Climate Friendliness.

Each car is scored on a scale of 1 to 10 for each category, then assigned an overall score.

The Nissan Leaf, for example, received a 9.5 out of 10, while the Chevrolet Volt received an 8.

The Leaf also edged out the Tesla Model S (which scored a 9 out of 10), thanks to its affordability and "Fuel Economy" (or energy efficiency) scores.

2013 Nissan Leaf

2013 Nissan Leaf

In addition, RideNerd provides "Benchmarks" based on independent testing and real world vehicle use.

These include EPA greenhouse gas and smog scores, and the projected annual cost of fuel, among other things.

There's also a listing of each car's plus points, along with an aggregation of outside reviews.

That proves handy when evaluating another common pair of new and green cars: the Ford C-Max Hybrid and Toyota Prius V.

Ford initially claimed victory in this high-roofed hybrid contest, because of the C-Max earned higher EPA fuel economy ratings.

Now, however, Ford has had to lower its MPG numbers to match real-world driving results achieved by the bulk of actual owners.

RideNerd rates the C-Max Hybrid and Prius V as almost equal; the Ford scored 7.9, the Toyota got an 8.

However, the site judges the Toyota to be greener to manufacture, with around 50 percent  less CO2 emitted per car. On the other hand, the Ford's superior driving range is considered a plus.

If you're buying a new car--or just want to spend an afternoon crunching numbers--head over to RideNerd to see how each new vehicle stacks up against the competition.


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