GM (and everyone else) may have to revamp product plans to hit 35 mpg

If the energy bill that's currently stalled in the US Senate does ultimately get passed, every car-maker in the US market will have to thoroughly revamp their product lines. This is particularly true for trucks where most companies struggle to achieve mileage even in the low twenties. At a Saturn event in San Diego CA, GM Vice Chairman Bob Lutz again said the 35 mpg would cause a $6,000-7,000 increase in vehicle prices in order to add the required technology that would meet the standard by 2020. That may well be true if people expect vehicles the size of a Chevy Tahoe to hit 35 mpg. According to Lutz, large crossovers like the Saturn Outlook couldn't meet that standard under any current circumstance. If fuel prices increase dramatically over the next decade (a likely scenario) buyers may adjust their expectations and start going for smaller cars instead which wouldn't require the same level of upgrades.
The reality is that while GM and other car-makers will be making major changes to their vehicles, they probably won't be making huge changes to their plans at this point. Everyone knew what was coming, and have almost certainly factored that into long-term plans by now. In spite of Lutz's scare-mongering, the Alliance of Automobile Manufacturers, which includes all the major car-makers has endorsed the energy bill, mainly to get something out there that they can start working toward.

[Source: Automotive News - Sub. req'd]