The popularity of hybrid vehicles will depend on whether or not US auto sales increase beyond its current levels, according to a statement from Audi engineer Marius Lehna to Reuters. Despite rising fuel prices, the German car maker will only expand its hybrid range if the market development improves because of the limited predictability of future trends.

Currently, 70 percent of worldwide hybrid sales, which stand at 283,000 units, are sold in the US alone. However, this pales in comparison to the country’s annual sales of between 16 and 17 million. If this rate doesn’t change, “it could become increasingly difficult to manufacture and sell hybrids in commercially sensible volumes,” commented Lehna.

The problem lies in the fact that, commonly, only people in their mid- to late-50s earning over $100,000 annually actually buy hybrids. According to Lehna, "it’s by no means the young, dynamic consumers that buy a hybrid vehicle but rather an intellectual upper class." Despite the grim view, Audi aims to launch its Q7 SUV hybrid, which was developed in a partnership with Porsche, by 2008.