DETROIT – Signaling fuel-economy concerns are making an impact in the luxury market, General Motors Corp.’s Cadillac division let it be known last week that Cadillac will be using four-cylinder power for its upcoming new entry-level model, according to The use of four-cylinder engines is something of a line in the sand in the luxury market, an option consumers in the past have embraced with mixed results. And believing four-cylinder engines imply a frugality and dearth of “power” inconsistent with the nature of the beast, many luxury marques — in recent years of low U.S. fuel prices, at least — have steadfastly refused to cross the line into small-engine territory.

Excluding its very early days, Cadillac dabbled with 1.8- and 2L four-cylinder power with the famously awful Cimarron (1982-88), but today’s four-cylinders are vastly more powerful and refined than anything available during the Cimarron vintage. So in light of high fuel prices and evolving buyer sentiment about the environmental correctness of small engines, Cadillac must feel more confident about the climate for revisiting four-cylinder power with its planned 2010 rear-drive sedan.

The new model will sit below the division’s current entry point, the CTS, and roll on GM’s coming new global rear-drive architecture.

Audi of America Inc., which long has offered four-cylinder gasoline engines with the high power densities that can satisfy American customers, seems to be one automaker well-placed to address U.S. engine-downsizing trends, according to Audi product and technology spokesman Christian Bokich tells AutoObserver the four-cylinder sales mix for the three model lines (A3, A4, TT) in which Audi’s 2L engine is available is running at 80 percent.

BMW AG and Mercedes-Benz currently offer no four-cylinder engines for any U.S. model. Europe’s Saab Cars and Volvo Cars have stayed close to their utilitarian roots and offer several four-cylinder models. As with most luxury brands expecting to make four-cylinder powerplants a viable play, turbochargers inject most Volvo and Saab four-cylinder powerplants with both the added power and technical chops the segment demands.