MILWAUKEE – The use of diesel engines in the high-volume (largely delivery truck) market is expected to head into decline in 2007. This is the view of David Hudson, director of Business Development for AVL Powertrain Engineering Inc., Plymouth, MI.

Hudson says the expected cost of new emissions aftertreatment for diesel engines – largely in the 6L to 7L category – will be $2,500 to $3,000, assuming a technically feasible system can be perfected, which so far has not occurred.

GMC C-Series

Hudson believes savvy operators of large fleets will calculate that the higher fuel cost for gasoline engines (hence more energy used) will be more economical on a vehicle/engine lifetime basis than the considerably higher initial cost of diesel engines that incorporate the required new emissions controls.

He says large-fleet operators of Class 8 diesels will have to make do with the new requirements as best they can.

As for the fast-growing use of passenger-vehicle diesels in Europe, Hudson attributes this to the requirement for a 25% cut in new-vehicle fleet fuel use by 2004; European auto makers are at about 18% now. But in order to push this forward, diesel-powered vehicles are being sold at less than normal markup.

Whereas the premium for a diesel car now is about $1,000, at comparable markup versus gasoline power, Hudson says the diesel premium should command in excess of $2,000. He believes the markup will increase, however, as diesels achieve greater market penetration.

Looking to the future, Hudson says HCCI (homogenous-charge compression ignition) gasoline engines produce insignificant oxides of nitrogen and particulate emissions that require no aftertreatment system. But controlling HCCI during transient-load situations has yet to be adequately achieved. Some hydrocarbon emissions aftertreatment will be required for HCCI diesels, but he says this is handled by straightforward, off-the-shelf technology.

This brings to mind information released by AVL some time ago on its CSI gasoline system, which employs HCCI at up to 3,000 rpm and 87 psi to 116 psi (6 to 8 bar) brake mean effective pressure and then switches to normal stoichiometric operation at higher speeds and loads.

The fuel economy gain in HCCI mode was then reported to be 20% to 25%, with insignificant engine-out NOx and PM emissions.