Diesel models may account for half of all vehicle sales in Europe but in the U.S. their numbers still hover around the 3% mark. Petrol-electric models, meanwhile, sell in even lower numbers with total sales in the U.S. only accounting for a meager 2.2% of the market. Despite their low popularity in the U.S., analysts are predicting sales of the efficient vehicles to more than triple in coming years but prices are expected to remain high.

Carmakers will be increasing the number of diesel and hybrid models they sell as they try to reach the 2020 35mpg fleet-average fuel economy target set by the U.S. government. This, according to J.D. Power and Associates, will see sales of hybrids leap to 7% by 2015 and sales of diesels grow to about 10% of the market by the same date.

The research body also predicts sales of four-cylinder models to eventually outpace those of more powerful V6 and V8 cars and trucks, while the longtime trend in rising vehicle weights is also tipped to end.

Speaking with The Detroit News, analyst Mike Omotoso explained that carmakers will have to face rising development costs because on average hybrids and diesels cost more to produce than their regular petrol models. Omotoso estimates that it will cost carmakers on average $4,000 to $5,000 per vehicle just to meet the 35mpg standard, and this cost is likely to be passed on to consumers.