The only difference is one of time: Although electric propulsion is very fuel efficient, it is slower due to power limitations.

唯一不同的就是时间：尽管电力推进器是非常高效燃料，它还是取决于能量的限制。

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It is very efficient and offers great fuel economy, and its only byproduct is water, so it's also a 'green' aircraft.

它非常有效，提供绝佳的燃油经济性，其唯一的副产品是水，所以它也是一架绿色飞机。

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We have made immense progress in the development of energy-efficient products, one example of which is the very latest fuel-saving hybrid technology.

我们在高效率产品研发方面取得了显著进步，其中的一个例子就是我们最新开发的可大大节约燃料的混合动力技术。

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At the same time, some gas-only models have become very fuel efficient.

NPR: The Prius Rules Hybrids �� but Is Interest Falling?

It first flew in 1989 and went on to become the best selling 30-seater plane ever made - in part because it is very fuel efficient and has half the running costs of a regional jet.

BBC: Saab's 'special mission' aircraft searches for customers

Thanks to the efficient turbocharged, common-rail, direct fuel-injection diesel engine, the concept car is still very fuel-efficient.

ENGADGET: VW unveils CrossBlue plug-in SUV with iPad mini headrests and 85MPGe efficiency (eyes-on)