So you're in the market for a new car. Fantastic.

You've done the research--looking at list prices, EPA fuel ratings, and all manner of other factors--and you know you want something fuel-efficient and easy on the environment.

But what will that car really cost over, say, five years of ownership?

We've done the math for you on five different types of cars, all of them significant models in the market.

For an efficient gasoline vehicle, we chose the 2012 Chevrolet Cruze Eco compact sedan. Regular hybrids, of course, have to be measured by the 2012 Toyota Prius liftback.

The Volkswagen Jetta TDI flies the flag for diesel,  the 2012 Chevy Volt takes care of plug-in hybrids and range-extended electric vehicles, and electric cars are represented by the 2012 Nissan Leaf.

First, some ground rules

All cars here are bound by the same rules, for consistency.

All base figures have been taken from the website today, which not only means they're based on the same measurements EPA tests are done with, but that you can head to the website to compare other vehicles on the same scale.

Fuel prices are $3.79 for gas, $4.04 for premium, $4.09 for diesel, and a U.S. average rate of $0.12 per kilowatt-hour of electricity. The site assumes 15,000 miles driven per year, with a 45 percent highway, 55 percent city split.

One important thing to note: We can't predict the future. Gas prices are expected to climb over the next five years. The more fuel-efficient a car is, the less it will cost you in the future if that happens. For comparison (and our own sanity) we'll freeze gas prices for the next five years.

Make sense? Great! Let's get started.

1. 2012 Chevrolet Cruze Eco - 28 city / 42 highway / 33 combined (MPG)
Price $19,325 - Gasoline $8,500 over 5 years - TOTAL $27,825

Should you go for a regular, efficient gasoline engine? That's a tough call. It's certainly cheaper overall than any other option here - an MSRP of $19,325, with cheaper fuel costs than the Jetta. You may save even more, as owners are averaging 38.6 MPG, so five-year fuel bills could be as low as $7,364.

Gasoline engines are typically cleaner than diesels, but the Cruze Eco hits the same 6/10 as the Jetta TDI for the California smog score. CO2 emissions are lower though, and you'll use six fewer barrels of oil. These figures all apply to the more efficient, manual-transmission Cruze Eco.

2. 2012 Toyota Prius - 51 city / 48 highway / 50 combined (MPG)
$23,015 - Gasoline $5,750 over 5 years - TOTAL $28,765

2012 Toyota Prius

2012 Toyota Prius

And so, to the old favorite. The Prius is the default green car, and it's still one of the cleanest vehicles on the road. That's borne out by the 9/10 California smog rating, and emissions of only 14.5 tons of CO2 over five years.

Owners are beating the 50 MPG combined rating too, getting 51 MPG on average. That lowers the five-year fuel cost from $5,750 to $5,573. And with economy that good, it'll prove cheaper than a Jetta TDI to run over five years, and almost as inexpensive as the cheap-to-buy Cruze.

3. 2012 Volkswagen Jetta TDI - 30 city / 42 highway / 34 combined (MPG)
Price $22,775 - Diesel $9,000 over 5 years - TOTAL $31,775

2012 Volkswagen Jetta GLI

2012 Volkswagen Jetta GLI

We've discussed before here that the Jetta's EPA ratings might be a little pessimistic, and judging by owners' reports, that's certainly the case.

Based on the official EPA figures, you'd spend $9,000 over five years on diesel. Taking owners' average MPG of 44.9, you'd spend only $6,832 - certainly a difference worth taking into account.

Add the $22,775 purchase price and your total, five-year bill is between $29,607 and $31,775.

Environmentally? Diesel has come a long way, but the Jetta still only scores an EPA rating of 6/10 for smog. You'll get through 56 barrels of oil in five years, and puff out 25 tons of CO2, with a further 6.5 tons of upstream greenhouse gases.

4. 2012 Nissan Leaf - 106 city / 92 highway / 99 combined (MPG equivalent)
Price $35,200 - Electricity $3,000 over 5 years - TOTAL $38,200

2012 Nissan Leaf winter test

2012 Nissan Leaf winter test

If you're looking at electric cars, then you'll almost certainly have some concerns for the environment as motivation. The good news starts here: With an EPA smog score of 10/10, zero greenhouse gas emissions and using the equivalent of only one barrel of oil to power over five years, the Leaf is an incredibly clean way to travel - and that's before you consider the lack of noise pollution too.

But how about costs? Well, the low electricity cost means on power alone it's the cheapest here. However, with an MSRP of $35,200 pre-local and government incentives, the five year cost is still high - $38,200. The more incentives you're eligible for in this case, the better.

Throw in low maintenance costs - not much more than wipers and tires - and for the first five years at least, running costs will be low. Battery life is a relative unknown.

If you're able to benefit from the $7,500 Federal income-tax credit, the cost of the Leaf falls to $30,700 over five years - enough to rise past the Jetta TDI into third place. Throw in local incentives and it may even rival the Prius and Cruze on cost.


5. 2012 Chevrolet Volt - Electric: 95 city / 93 highway / 94 combined (MPG equivalent); Gas: 36 city / 37 highway / 36 combined (MPG)
Price $39,145 - Premium gasoline $8,250 - Electricity $3,250 - TOTAL From $42,395

2012 Chevrolet Volt

2012 Chevrolet Volt

Two Chevys in our list? Unavoidable, when one is the Volt range-extended electric car. For the purposes of argument, we're classifying it as a plug-in hybrid. It's also - by far - the most difficult to determine ownership costs.

Why? Because of its two separate MPG ratings with the EPA. If you use exclusively electricity, you'll only spend $3,250 over five years on charging it. On premium gasoline alone, $8,250. And since owners are averaging an equivalent of around 130 MPG, neither of the EPA's figures are accurate.

What is fairly safe to say, is that based on current Volt ownership, the running costs should be significantly lower than those quoted on the EPA website.

And like the Leaf, if you're eligible for the $7,500 Federal tax credit (and perhaps other incentives as well), you can take $7,500 or more off the price.

Decisions, decisions

So what vehicle should you go for?

Ultimately, it's down to personal preference - the five cars assembled here are quite different vehicles, both to drive and to own. There are other costs to consider too, of course, such as insurance and servicing.

With regards to the latter, the Cruze should be relatively inexpensive to insure and service, and the Prius is proving hugely reliable and can also handle large distances.

Diesels typically require a little more regular maintenance than other vehicles, but if looked after they're capable of huge mileage. Although the Volt is a complicated vehicle, the more you use that electric motor, the less wear the engine will see.

The Leaf should prove inexpensive to service. It has no oil, nor coolant, the regenerative braking should keep rotor wear to a minimum, low rolling-resistance tires are fairly tough, and you won't be replacing any air filters. But longer-term servicing is still a relative unknown.

If you can afford to buy the Leaf and rarely drive longer distances, it's the greenest of the bunch. But on costs, it's hard to argue against the Prius. And a gasoline car may still be cheapest.--if you think gasoline will stay where it is today over the next five years.

Do you?

Leave us your thoughts in the Comments below.


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