It might be easy to say the world’s auto makers are all over the map with regard to fuel- and emissions-reducing technology.

There are many specific initiatives, but they all spring from the same basic camps. A brief analysis of major auto makers’ “green” technology:

U.S.

General Motors

Top prospect: Burgeoning hybrid-electric vehicle (HEV) lineup that incorporates low-tech, low-cost belt-driven alternator technology and pending “2-mode” HEV transmission – being developed in conjunction with DaimlerChrysler AG and BMW AG – that has Toyota-trouncing potential.

Longshot: Continuing hydrogen fuel-cell vehicle (FCV) research about which there has been little fresh discussion. Recently announced ethanol (E85) initiative with corny advertising campaign that glosses over liabilities.

Ford Motor Co.

Top prospect: A promised fleet of 250,000 HEVs by 2010, but still could get caught lagging in the HEV technology race. There are rumors it may join GM 2-mode HEV development joint venture (see above).

Longshot: Flashy E85 push as myopic as GM’s. Ongoing research into hydraulic hybrids.

DaimlerChrysler/Chrysler Group

Top prospect: Last year joined GM-led joint-development of “2-mode” HEV transmission. DC’s European masters are known to dislike HEV solution, however.

Battling for budget: Mercedes-Benz unit’s plan to make BlueTec “clean” diesel a worldwide phenomenon. Technology works, but faces cost and perception issues, particularly in U.S.

Europe

BMW AG

Top prospect: Tossup between participation in GM-led HEV development joint venture and escalating diesel developments. New diesels are spectacular, but emissions compliance is costly.

Longshot: BMW for years has tinkered with hydrogen-fueled internal-combustion engines. Ongoing demonstrations have produced little traction.

PSA Peugeot Citroen

Top prospect: Recently unveiled diesel HEVs that it says can be markedly more fuel-efficient than current gasoline-engine jobs – enough so to make the suspect mileage numbers a reality.

Longshot: French auto makers have a long tradition with battery electric vehicles. Continuing battery research could finally yield a viable electric car – at least for those without transcontinental range requirements.

Porsche AG

Top prospect: Plans to get into the HEV game with somebody else’s technology. Toyota used to be the likely partner, but the GM/DC/BMW development triumvirate is a distinct possibility.

Volkswagen AG

Top Prospect: Diesel, but may have to play the HEV card if perception of HEV technology remains strong in the U.S.

Japan

Toyota Motor Corp.

Top Prospect: HEVs, of course. But unless the technology – and its price – can be improved to match original promise, Toyota could face a backlash.

Honda

Top prospect: HEVs, although seriously lagging Toyota’s PR lead. Do not discount this engineering-obsessed company’s ability to close the gap, however.

Longshot: Has made new noise about diesel, at least for the U.S.

And continuing FCV research appears promising.

Nissan Motor Corp

Top prospect: Styling. To now, great sheet metal has meant nobody cares about environmental credentials. Grudgingly launching HEV Altima (using Toyota componentry) later this year.

Longshot: Staying on the sidelines long enough to make sense of it all.

Fuji Heavy Industries Ltd. (Subaru)

Top prospect: Unique HEV using proprietary lithium-ion batteries and, eventually, Li-ion capacitors. Launching in Japan in 2007.