Fuel saver

Hybrid electric vehicles have saved close to 230 million gallons of fuel in the US since 1999, according to a report from the National Renewable Energy Laboratory (NREL).

‘Sales of hybrid electric vehicles have increased an average of 72 per cent a year for the past five years and in 2006 the average fuel economy based on new EPA estimates was 35 miles per gallon for new hybrid models sold in the US,’ said Kevin Bennion, an NREL vehicle systems analysis research engineer.

To estimate the total fuel saved by hybrid electric vehicles, NREL researchers combined hybrid electric vehicle sales and fuel economy data to determine fuel savings. The fuel economy data included new EPA mpg ratings, but old EPA mpg ratings and user-reported values were also reviewed.

VISION modelling software developed by Argonne National Laboratory was used to determine the total number of hybrid electric vehicles in use in a given year. The annual vehicle stock estimates and the vehicle sales data were combined to calculate fuel savings of replacing a conventional vehicle with a hybrid closely matched in terms of size, weight and performance.

In 2006, the average fuel economy improvement for hybrid electric vehicles over the replaced conventional vehicle was approximately 45 per cent.

Even with this improvement, hybrid electric vehicles would have to replace a significant portion of the total light duty vehicle fleet to have an impact on petroleum imports. For example, net imports of oil in 2003 were 11.24 million barrels per day, and 8.55 million barrels per day went to light duty vehicle use.

‘Although the fuel savings from hybrid electric vehicles to date is relatively small compared to the total fuel use, as the technology matures and these numbers increase they can have a significant impact in reducing our overall transportation fuel use,’ said NREL senior research engineer Matthew Thornton.