LOUD music, fog machines and an often blinding light show. You’ve either stumbled into a Van Halen tribute band concert or you’re at an auto show press conference.

Exuberance began and ended with the theatrics of unveiling cars. The tone was predictably somber as even the less-belabored auto manufacturers talked of dark economic times running hard up against their stated desire to build and sell green mobility. Toward that end, most of the vehicles getting star treatment were efforts at being economical and eco-friendly.

Every manufacturer touted their effort as the best approach, while also saying that it wasn’t the only way to be green. That means, for instance, VW and Audi could tout clean diesel as the way, while Hyundai bragged that they’ve leap-frogged everyone else on lithium battery technology.

Underlying all this cleanliness is the grimy truth that the industry as a whole, and the Detroit wing in particular, is faltering. Sales slumped to a quarter-century low in October. GM has stopped development on several vehicles, including models that were to be part of the company’s press conference here, which was canceled.

Renault/Nissan chief executive Carlos Ghosn put the finest point on the issue of the economy and tight credit markets in his keynote speech.

He made no bones about the industry’s need for long-term financing at reasonable interest rates if the desire for zero-emission vehicles is to be achieved. With no long-term credit available in today’s market, Ghosn said governments must step up. He emphasized that such financing is completely separate from any bailout of the Detroit automakers.

While Ghosn and other executives stressed that the automobile industry will survive the recession, there was still plenty of room for uncertainty.

“The usual rules of the automobile business are up in the air,” he said.

The breathability of that air is open to question.