This week, electric car maker Tesla Motors cut its revenue forecast and announced it would be selling 5 million shares of stock to raise capital. Some are beginning to question the long-term viability of the automaker and its line of green cars. Nevertheless, according to Edmunds.com, 43 new hybrid, plug-in hybrid, battery-electric, diesel and fuel-cell electric vehicles will be introduced to the U.S. market by the 2015 model year.

Read: The 10 Best-Selling Hybrid Cars

Despite Tesla’s woes, hybrid cars, by many measures, are going strong. Through the first six months of this year, Toyota sold 117,626 of the Prius family units, just 12,080 vehicles shy of its 2011 full-year total. Edmunds.com estimates that market share of alternative fuel vehicles will rise from roughly 3% in 2012 to nearly 5% by 2015. Using sales data provided by Edmunds.com, 24/7 Wall St. reviewed the 10 best-selling hybrid cars for the first half of the year. These 10 models alone account for more than 90% of total alternative-energy vehicles sold.

The vast majority of electric and hybrid vehicles sold in the U.S. were built by Asian-owned companies. Only two, the Ford Fusion and the Chevy Volt, are manufactured by American-owned companies. The combined sales of those two models are less than 11,000 units for the first six months of 2012. Meanwhile, the Toyota Camry alone has sold nearly twice that. The Prius family has sold more than 10 times the two most popular American alternative-energy models. If the market for alternative energy vehicles does indeed pick up, American car manufacturers will be behind.

According to Edmunds.com representative Ivan Drury, the projected growth in the share of alternative energy vehicles has little to do with the increased viability of hybrid or electric cars as money-savers and more to do with there being more hybrid cars available on the market. Drury added that the increasing improvement of efficiency in combustion vehicles has hurt the viability of purchasing a hybrid or electric vehicle. “Unless fuel costs get very expensive, you’re not going to see a huge leap in the sales of these types of cars.”

It appears that at current gas prices, the benefits of current models — that is, the amount drivers can save on fuel vehicles — is marginal, especially when compared to the higher sticker price they are paying for hybrid and electric vehicles. Edmunds.com estimates that at the current level of gas savings from purchasing a 2013 Ford Fusion hybrid versus a regular 2013 Fusion, it would take 6.9 years for the costs to even out.

Edmunds.com provided 24/7 Wall St. with a list of the first six months of 2012 U.S. sales for full hybrids, electric and plug-in hybrid vehicles. Other types, including cars that are combustion-based, with only mild hybrid drivetrains, were not included. For the purposes of the Toyota Prius, which includes four separate vehicles — the Prius, the Prius V, the Prius C and the Prius Plugin — the model was only listed once. Reviews of these models were from Consumer Reports and Car and Driver. Fuel efficiency came from the U.S. Department of Energy’s site, FuelEconomy.gov. Fuel efficiency and prices refer to the 2013 model of each car, or 2012, if 2013 was not available.

These are the 10 best-selling hybrid cars.
10. Ford Fusion Hybrid
> 2012 sales: 3,182
> Type: Hybrid
> Starting price: $27,200
> EPA fuel efficiency: 47 mpg (combined)

The Ford Fusion Hybrid is the only alternative fuel vehicle on this list from Ford Motor Co. (NYSE: F), although the company offers three other hybrid vehicles. The model has sold well, exceeding 12,000 cars sold in both 2009 and 2010, its first two years on the market. In 2011, however, sales fell by about 40% to 7,613 units. The model has the third-strongest fuel efficiency of any non-plug-in hybrid on this list after the standard Prius and Prius C. Among family cars, the 2012 Fusion Hybrid received the highest owner satisfaction score from Consumer Reports.

9. Honda Insight
> 2012 sales: 3,711
> Type: Hybrid
> Starting price: $18,500
> EPA fuel efficiency: 42 mpg (combined)

Despite being one of the least expensive top-selling hybrids, customers have soured on the Honda Insight. After selling more than 20,000 units in 2010, Honda Motor Co. Ltd. (NYSE: HMC) sold less than 4,000 during the first half of 2012. Reviews for the 2012 Insight were not positive. “The ride is stiff and choppy, and road noise is pronounced,” Consumer Reports noted. In its owner’s satisfaction survey, the car was rated worst among fuel-efficient hatchbacks. However, fuel economy exceeds 40 mpg, and it is one of only two cars on this list, alongside the Prius C, with a price below $20,000.

Also Read: The Biggest Gas Guzzlers on the Road

8. Honda Civic Hybrid
> 2012 sales: 3,879
> Type: Hybrid
> Starting price: $24,200
> EPA fuel efficiency: 44 mpg (combined)

In 2008, Honda sold more than 30,000 Civic Hybrids. The next year, sales were down by more than 50%, and by 2011 it sold fewer than 5,000 units. So far in 2012, the carmaker already has sold almost 4,000 Civic Hybrids, and seems likely to exceed 2011 car sales. The model is one of six alternative fuel vehicles offered by Honda. Another is the Civic Natural Gas, which according to Car and Driver, is the only compressed natural gas vehicle available to the American public. The Indianapolis Star recently reported that Honda will begin manufacturing Civic Hybrids domestically, in Greensburg, Ind., by spring 2013.

7. Kia Optima Hybrid
> 2012 sales: 4,501
> Type: Hybrid
> Starting price: $25,700
> EPA fuel economy: 37 mpg (combined)

From its debut in November 2011 through June 2012, Kia sold 6,660 Optima Hybrids. The only hybrid made by Kia sells at a starting price $4,500 higher than the standard 2013 Optima. The hybrid model is considerably more fuel efficient, driving 37 mpg versus 26 mpg for the regular model and costing the average driver $650 less per year, based on calculations by the Bureau of Energy. The Optima Hybrid has the same gas mileage, the same powertrain and almost the exact same starting price as the Sonata Hybrid manufactured by its affiliate company, Hyundai.

6. Lexus RX Hybrid
> 2012 sales: 5,065
> Type: Hybrid
> Starting price: $45,910
> EPA fuel economy: 30 mpg (combined)

Perhaps no luxury car maker has embraced alternative fuel vehicles as Lexus, which offers five hybrid models. The RX Hybrid’s starting price is $10,000 more than any other top-selling hybrid. The car gets just 30 mpg overall, and just 28 mpg on the highway — lower than many nonhybrid vehicles. The model still offers far better mileage than Lexus’s main SUV, the RX 350, which gets just 21 mpg. There are safety concerns for previous model years. In June, Lexus issued a recall for the 2010 model to address problems related to unintended acceleration caused by floor mats interfering with accelerator pedals.
5. Hyundai Sonata Hybrid
> 2012 sales: 7,414
> Type: Hybrid
> Starting price: $25,850
> EPA fuel economy: 37 mpg (combined)

In 2011, after delaying the release of the Sonata Hybrid to remove a feature that would have allowed drivers to turn-off virtual engine noise, Hyundai sold 9,667 units. Halfway through 2012, the Sonata Hybrid appears to be on pace to exceed last year’s sales. The car is presently Hyundai’s only hybrid model and costs almost $5,000 more than the standard 2013 Sonata model. Though the hybrid has far better gas mileage, at 37 mpg versus 28 mpg for the regular Sonata, the hybrid’s annual fuel cost of $1,550 is only $500 less than that of the regular model.

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4. Chevrolet Volt
> 2012 sales: 7,548
> Type: Plug-in Hybrid
> Starting price: $31,645
> EPA fuel economy: 37 mpg (combined)/98 mpg (equivalent) electric

The Volt is the country’s best-selling plug-in hybrid. After selling 6,096 units in 2011, Chevrolet may double sales in 2012, as it already sold more than 7,000 cars in the first six months of the year. The Volt has a range of just 38 miles when using electricity and 380 miles when using both electricity and gasoline. The annual fuel cost for the plug-in is only $950, according to Bureau of Energy calculations. The 2012 Volt earned accolades as a top safety pick from the Insurance Institute for Highway Safety.

3. Lexus CT Hybrid
> 2012 sales: 8,647
> Type: Hybrid
> Starting price: $31,850
> EPA fuel economy: 42 mpg (combined)

Through the first six months of this year, the Lexus CT Hybrid has been the best-selling hybrid model made by any luxury brand. At a starting price only $205 higher than the Chevrolet Volt, it is also the cheapest of the five hybrids offered by Lexus. Not only relatively inexpensive and fuel efficient, the 2012 CT Hybrid was also an IIHS top safety pick. Despite these positives, Car and Driver’s review of the 2012 model described it as “painfully slow” and “an expensive Prius with better styling.” The CT Hybrid shares the same powertrain as the Prius, a less expensive hybrid manufactured by Lexus’ parent company, Toyota Motor Corp. (NYSE: TM).

2. Toyota Camry Hybrid
> 2012 sales: 21,466
> Type: Hybrid
> Starting price: $25,990 for Hybrid LE; $27,500 for Hybrid XLE
> EPA fuel economy: 41 mpg (combined) for Hybrid LE ; 40 mpg (combined) for Hybrid XLE

In the first half of 2012, Toyota sold more than 20,000 Camry Hybrids, which is more than twice as much as any hybrid model not made by Toyota. Sales of the car have declined in recent years. In 2008, Toyota sold 39,874 units, but only sold 8,157 in 2011. In 2012, however, sales have more-than doubled compared to 2011 in just six months. Two versions are available, the Hybrid LE and the Hybrid XLE. Both exceed 40 mpg, and neither has a starting price over $30,000. In reviewing the model, Edmunds.com noted that the model “shares all the attributes that make the conventional Camry one of the best-selling family sedans out there.”

1. Toyota Prius
> 2012 sales: 117,626
> Type: Hybrid and plug-in
> Starting price: $24,000
> EPA fuel economy: 50 mpg (combined)

The Prius is by far the best-selling alternative fuel vehicle in the United States, with total sales of well over 100,000 through June of this year alone. Four versions of the Prius are available, three hybrids — the standard version, the Prius C and Prius V– and one plug-in electric. Each of the four versions would a best-seller individually. Last year, the total number of sales for all four versions was 129,706, a figure Prius may well exceed this year. Owning one is relatively cheap. The only alternative-fuel model on this list with a lower starting price than the standard Prius is the Honda Insight, while no model is cheaper than the Prius C.

Alexander E. M. Hess and Michael B. Sauter

Also Read: Cars with the Most Safety Complaints

Correction: In a previous version of this article, we indicated that Tesla manufactured hybrid vehicles. In fact, Tesla only manufactures combustion-free vehicles.

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