Finnish Researchers Find Little Difference in E10, E5 Fuel Consumption

Finnish researchers say there is no significant difference in vehicle fuel consumption between E10 (10% ethanol) and E5 gasoline.

The VTT Technical Research Center of Finland, located at the Helsinki University of Technology in Otaniemi, says its findings are based on a study using six used cars of different makes under laboratory conditions.

’10 Audi A4 1,8T FSI among models tested.

The researchers say there have been public claims that fuel consumption is significantly higher with 95 E10 gasoline (95 octane gas containing a maximum of 10% ethanol) than with its predecessor 95 E (Eurograde) or the 98 E5 now on the market.

The suspected higher consumption has deterred drivers of cars whose manufacturers recommend E10 from actually using the blend.

"The point of this study was to highlight how fuel consumption should actually be measured to give comparable results,” VTT principal scientist Juhani Laurikko says in a statement.

“Measuring fuel consumption very accurately is not as simple as it seems, because other factors affect consumption besides the fuel, itself. In laboratory conditions, we can eliminate these other factors.”

The VTT measurements show the cars tested on 95 E10 fuel used an average of 22.8 mpg (10.3 L/100 km), as opposed to 22.9 mpg (10.23 L/100 km) when using 98 E5 fuel.

The researchers say this means using 95 E10 gasoline with its higher ethanol content, increases consumption 0.7%.

Normalizing measurement results of each individual test run with observed slight scatter in actual total work done over the driving cycle yields to a somewhat higher overall difference of 1.0%.

VTT obtained all the fuel used for the test runs at the same time from the Otaniemi Neste Oil service station in Espoo. The fuel was qualified by the Finnish Customs Laboratory to ensure ethanol content met specifications.

VTT says it performed the comparison test under controlled laboratory conditions, because of practical and almost insurmountable difficulties in measuring a car's fuel consumption accurately and repeatability in normal driving.

The researchers say their results show the public claims concerning differences in fuel consumption may be due to any number of other factors besides the type of fuel used.

The study involved six gasoline-powered cars loaned by VTT employees. The vehicles ranged from the ’99 to ’10 model years and, according to the auto makers’ recommendations, compatible with E10 fuel.

They included a ’99 Peugeot 406 and Alfa Romeo 156, ’02 Saab 9-5, ’04 Honda Accord, ’09 Nissan Qashqai and ’10 Audi A4 1,8T FSI. The cars were checked to ensure they were free of any faults or malfunctions that could influence test results.

VTT measured fuel consumption using what it says was the simplest and most reliable method: measuring the weight of fuel consumed. As the density of the fuel grades was known, establishing the volume of fuel consumed was a simple matter.

The road test featured aggressive accelerations and a high average speed. Two qualified drivers were used, and each car was driven by the same driver in all tests. Two tests were conducted on consecutive days for each gasoline grade.

The study is a part of a 5-year research program to make energy used in road travel more efficient, develop emissions-reducing technologies and commercialize the results of the development work.