TRAVERSE CITY, MI – The long-discussed diesel revival in the U.S. is occurring right now, according to supplier Robert Bosch.

In January 2009, only one in 10 U.S. customers who had a choice to buy a diesel chose one, says Alexander Freitag, director-diesel systems engineering for North America. In May, that number had increased to one in three.

In 2006, he tells the Center for Automotive Research’s Management Briefing Seminars here, only 13% of all customers would consider a diesel. In May, that was up to 29%.

Modern turbocharged diesels can meet emissions targets, and Freitag says their higher cost is actually amortized faster by higher resale values. A diesel-powered car saves $3,600 in fuel costs after three years and a pickup saves $3,100.

The fuel efficiency advantage and the government’s 2025 fuel-efficiency goal will bring more diesels to North America, predicts Steve McKinley, Honeywell Turbo Technologies vice president-engineering for the Americas. “If I were in an auto maker’s shoes, I would take a good look at developing light-vehicle diesels.”

Diesel penetration in Europe grew from 20% to 50% after Bosch invented the common-rail fuel-injection system, which allowed injection pressures to rise. In North America, Frietag says, the offer will increase substantially in the next several years, with more than a dozen new models offering diesels in 2013.

Both Honeywell and Bosch believe the internal-combustion engine has a long life ahead because both can improve fuel economy substantially.

Freitag says the diesel has potential to improve another 25%-30%, mainly through downsizing and lower-speed operation, as well as incremental improvements in all areas of combustion, including Bosch’s method of rounding out fuel-injector nozzle holes.

Gasoline engines can gain up to 47% in efficiency, he says, via hybridization and turbocharging. A hybridized diesel using 20% biodiesel fuel can improve from the diesel baseline by 52%, and diesels already match the fuel efficiency of a plug-in gasoline hybrid.

Turbocharged gasoline engines are at the beginning of a decade-long explosion, says McKinley. While diesel turbocharging globally will increase by 6% a year through 2015, boosting of gasoline engines will be explosive.

In the U.S., he says, 82% of gasoline engines will be turbocharged in 2020, up from 5% in 2009. Worldwide, turbo and turbo hybrids will have 56% of all engines in 2020, up from 21% in 2009.

In Western Europe, where 65% of vehicles are turbocharged, penetration will rise to 69% this year, thanks to growing numbers of gasoline direct injection engines.

“There is tremendous pressure on our customers to find technologies to meet these (fuel-efficiency) standards,” says McKinley, adding there will be only modest growth of non-boosted vehicles in the decade ahead. “We are very bullish on the longevity of the internal-combustion engine.”

Both Bosch and Honeywell are developing new technologies to improve their key products. Bosch is working on aftertreatment, injectors and raising common rail pressures to 36,250 psi (2,500 bar), and even higher for commercial vehicles.

Honeywell is working on new variable-nozzle technologies and ball-bearing improvements. While turbos already are using exhaust heat to drive their turbines, McKinley says engineers are “looking for more innovative ways to bring waste energy back to the powertrain.

“We have new products in the pipeline, with a continued emphasis on extending the life of the internal-combustion engine.”