In its 2014 Annual Energy Outlook, the U.S. Energy Information Administration is predicting most declines in conventional petrol vehicle sales over the next four decades, from 82% in 2012 to 78% in 2040.

But, it added, these will be vastly more efficient – 42% of all new cars are expected to be fitted with “micro-hybrid” technology, comprising stop-start systems and energy recuperation.

The predictions are more positive than in the 2013 report, which suggested an 80% share for petrol vehicles in 2040. However, most of the growth comes from alternative fuels rather than electrification. Cars and small vans using E85 ethanol are now predicted to account for 11% of sales in 2040, against 7% in last year’s report, while 4% will be diesel powered, up from 3% in the 2013 report.

By 2040, the EIA said it expects 5% of new vehicles to be full hybrids – a modest growth on the technology’s 3% share of 2012 vehicle sales. Plug-in hybrids and electric vehicles are predicted to have a 1% share each, while hydrogen fuel cell models are not included in the report.

The report’s revised predictions are based on fuel prices, expanded product offerings and the availability of E85 ethanol during the last 12 months.