Maybe this story can be attributed to President Bush signing into law last week new fuel economy standards that call for a 40 percent fuel economy improvement by 2020. Or maybe you could speculate that Cadillac feels that their current V-6 became the engine of choice on the 2008 STS because it’s so close in power to the V-8.

Either way you look at it GM has canceled plans to build a new advanced double overhead-cam V-8 for its luxury cars. The move means the future for Cadillac’s V-8 car engines is unclear.

GM announced about a year ago that they would invest $300 million in their Tonawanda, NY engine plant to build new V8 engines scheduled to start production in 2009. The engine would have been geared to replace the Northstar V-8.

Cadillac could be planning to switch to high-powered V-6s in its cars, except for the Corvette-based XLR.

The new direct-injected V-6 in the 2008 CTS throws 304 hp, while the current Northstar V-8 makes 275 hp in the 2008 DTS. With automakers concerned about weight to meet the evolving new fuel standards, the V-6 is about 150 to 200 pounds lighter than the V-8.