Nissan has joined a growing list of carmakers promising new ultra-fuel efficient models but, unlike most, Nissan is placing its bets on a conventional petrol vehicle. Where most carmakers are developing new hybrids, clean-diesels and electric cars, Nissan claims it will release a vehicle by 2010 for the Japanese market that can travel up to 100km on just 3L of ordinary petrol. This will allow it to keep the costs of the car low, giving it an advantage over expensive and potentially unreliable hybrids.

The news comes from Nissan executive Vice President Mitsuhiko Yamashita, who claimed the “fuel-economy of the 3-liter car will be at the same level as that of hybrids,” reports the Wall Street Journal. Though he wasn’t willing to divulge any details about the new model, we suspect it will feature some of the latest advancements in petrol engine technology including direct injection and possibly homogenous charge compression ignition (HCCI). Pictured above is Nissan's Urge, a concept of a future small sports model.

Volkswagen is also rumored to be developing a super-efficient vehicle. At this week's Frankfurt Motor Show, VW's Ferdinand Piëch hinted that a 100mpg VW could be on the market by 2010.