Despite being the first hybrid on the roads in America, the Toyota Prius still beats its contemporaries in terms of green performance, a study has shown.
The US Union of Concerned Scientists put a selection of hybrid models through their paces, releasing the results last week and observing that the Prius delivers more than 40 percent reduction in global warming pollution compared to its closest conventional (gasoline) counterpart.
The model, which UCS says consists of around half of all hybrid sales, far outperformed even its closest competitor in the "non-luxury" model category, the Honda Civic Hybrid, despite a host of hybrid vehicles now being available from US and international nameplates.
Among the luxury models, Toyota-owned Lexus topped the ranking with the new Lexus CT 200h coming in above the Lincoln MKZ hybrid - although Lexus accounted for an impressive four of the top five positions when it came to the best luxury hybrids.
While hybrid technology is improving all the time, the UCS has warned that in some cases, automakers are making the choice to maximize power over fuel economy.
In the worst example cited of this practice, the Volkswagen Touareg Hybrid SUV emitted only ten percent less global warming pollution than its gasoline counterpart, an all-time low on the score card.
The new Porsche Cayenne Hybrid and BMW's X6 and 750i ActiveHybrids were also singled out by UCS for offering the least in terms of environmental improvement among their peers.
America's best hybrids
Model - Combined MPG, Environmental Improvement Score (out of 10 - how the model compared with its conventional gasoline counterpart)
1. Toyota Prius - 50 mpg (4.70 l/100km), 9.2
2. Honda Civic Hybrid - 41 mpg (5.74 l/100km), 7.2
3. Honda Insight - 41 mpg (5.74 l/100km), 6.5
4. Ford Fusion Hybrid - 39 mpg (6.03 l/100km), 7.8
5. Hyundai Sonata Hybrid - 37 mpg (6.36 l/100km), 6.8
6. Honda CR-Z - 37 mpg (6.36 l/100km), 6.2
7. Toyota Camry Hybrid - 33 mpg (7.13 l/100km), 6.1
9. Nissan Altima Hybrid - 33 mpg (7.13 l/100km), 5.7
10. Ford Escape Hybrid FWD - 32 mpg (7.35 l/100km), 7.0