"Rising oil prices coupled with concerns about global climate change are driving debate about which fuels and engines should be used to power the 17 million new cars and trucks sold each year," said John Graham, senior author of the research paper.
The research examines the benefits and costs of three alternatives to the gasoline-powered internal combustion engine for the period 2010-2020. They are gasoline-electric hybrid technology, advanced diesel technology, and dual-fuel vehicles that are powered continuously by E85 (a mixture of 85 per cent ethanol and 15 per cent gasoline).
Though each alternative has the technological potential for significant market penetration in the near term, the researchers also tried to find out which among the three can provide more societal benefits.
Their first finding suggested that light trucks and cars continuously fuelled by the E85 technology, compares unfavourably with the other two alternatives.
"Advanced diesel and hybrid technologies show very well in this study, in terms of benefits to the individual and society overall," said Graham. "E85 simply doesn't provide the same benefits," he added.
The study also included comparing each technology to a gasoline-powered vehicle, which included three vehicle types: a mid-sized car, a mid-sized SUV and a large pick-up truck.
The cost-benefit comparisons were made from the perspective of individual consumers and society in general, on a per-vehicle basis over the life of the vehicle.
The societal perspective included tailpipe pollutants, greenhouse gas emissions and "energy security costs" for the fuels, which are the costs to society as a whole from greater dependence on expensive and unstable foreign oil supplies.
The consumer perspective accounted for technology cost, fuel savings, mobility and performance. It found out that for all three vehicle types, the advanced diesel offers the highest savings over the life of the vehicle among the options considered. These savings increase with the size and fuel use of the vehicle.
On the other hand, the hybrid option has smaller but still considerable savings for SUV applications, moderate savings for pick-up applications, but minimal savings over the life of the vehicle for car owners.
The vehicles operating on E85 costs more over the vehicle life, with a greater net cost burden for larger vehicles and increased fuel consumption.
"While it is assumed that the hybrid vehicle will save more fuel than the advanced diesel, the overall advantage goes to the diesel because of its lower technology costs and better performance such as increased torque," said Graham. "For E85, it is the cost of producing the fuel, not vehicular changes, that drives the negative results," he added.
Based on these reasonable assumptions, the research paper placed advanced diesel technology as first, followed by hybrid technology, the gasoline engine and E85 technology.
Each alternative has the technological potential for significant market penetration in the near term.