Consumer attitudes toward diesel engines are becoming more favorable. According to the Morpace Powertrain Acceptance & Consumer Engagement (PACE) study, 62 percent of new vehicle owners feel that diesel powered vehicles have "gotten better" over the past 10 years. And more than one-third (35 percent) now say they will consider clean diesel technology for their next vehicle.

Owners of luxury cars and full-size pickups are most likely to consider clean diesel. This is due to perceptions of improved fuel economy and greater environmental friendliness, according to Bryan Krulikowski, author of the PACE study. Small car owners show least interest.

"While the perceptions of diesel have changed for the better, consideration of clean diesel vehicles is hampered by the high cost of diesel fuel compared to gasoline," says Krulikowski.

Fuel cost is the number one reason for not considering a diesel engine. Additionally diesels are viewed as noisy and smelly, "suggesting that some consumers recall diesels of the past and have not yet experienced or accepted the improved diesel technology available today," according to Krulikowski.

Also, even among clean diesel considerers, 62 percent say they need more information about usage of a liquid additive - such as urea - before determining whether or not they would still consider the technology.

"The urea issue could be a real sticking point for consumers," explains Krulikowski. "A lot of consumers are on the fence because they are unsure of the maintenance required for a clean diesel engine. Manufacturers need to take the guesswork out of this process by coupling it with other major service items like oil changes."