Hi Fritz. Why has GM recently been substantially increasing the mass of their mid-size vehicles (~500lbs)? Cars like the CTS, LaCrosse and Camaro are simply too heavy. They would move faster and be more fuel-efficient if they were lighter.

Here's the response: Mass is an important element in total vehicle performance for key attributes such as Fuel Economy, Stopping Distance, and Acceleration. Direct mass comparisons are more complex than they might appear given the impact of option content and compliance with future safety standards.
The industry has generally been trending to larger overall vehicle size and overall vehicle mass. Examples include the Honda Accord, Toyota Corolla and even the new Toyota Prius, which have all increased in size and mass, but the focus on reducing mass in the future is clear. In fact, many competitors have made their mass reduction goals very public.
Some of the increases are related to the growth in safety content to meet the increasing safety performance requirements. That said, we recognize that we must make significant improvements in this area. Our upcoming programs have aggressive mass targets and the Product Development Team is using both simple and advanced methods to deliver on these targets. Moving this metric to the forefront and driving efficient, high quality designs is foundational to our future product success. -Tom Stephens, Vice Chairman Global Product Development