Lightweighting Trend a Balance in Achieving Efficiency and Performance

One hard and fast rule in automotive design is that the quickest way to improve performance, increase fuel economy, and reduce emissions is to get the lead out. Automakers are going to great measures to reduce the weight of each new generation of vehicles they engineer. The problem is, consumer demand for more luxury and convenience features, coupled with new federal mandates for safety equipment and complex emissions systems, keeps driving the curb weight of vehicles up. That added content has increased the average weight of most models by a significant factor in the past decade alone.

Experts estimate that every additional 100 pounds of weight a vehicle carries can reduce fuel economy by one to two percent. Thus, an additional 500 pounds or more added to a vehicle platform can really kill economy and performance while hurting tailpipe emissions.

On a recent media trip to drive new Porsche models including the Cayenne Hybrid, the challenge automakers face became readily apparent. This high-end luxury SUV is loaded with all the bells and whistles you could ask for. Still, new legal requirements from our government coupled with additional customer driven product amenities added up to 158 pounds of bloat. Now, Porsche doesn’t launch a new vehicle unless it is an improvement over the previous model. In the case of the redesigned Cayenne, that required a serious weight reduction program.

Amazingly, the new Cayenne is nearly 400 pounds lighter than the previous model, yet more capable in every respect. When you add the additional 158 pounds to the equation, Porsche trimmed an incredible 554 pounds from vehicle. The result of careful engineering and the use of new lightweight materials provide impressive results. About 245 pounds of that was due to changes in materials and design, another 145 pounds was found in the chassis and suspension, and Porsche engineers trimmed 139 pounds from the powertrain.

Big deal, you say? One drive in the new Cayenne is convincing. Every model from the base Cayenne to the Diesel, Cayenne S, and Cayenne S Hybrid on up to the mighty 500 horsepower Cayenne S Turbo is quicker and more agile, while delivering better fuel economy with lower CO2 emissions.

Clearly, the message for everyday driving is to avoid carrying more stuff around than you need. Get the junk out of your trunk and clear clutter out of the cabin. An extra hundred pounds matters. Interestingly, a gallon of gasoline weights roughly six pounds and diesel is a little over seven. When your tank is full, the car won’t perform quite as well as when it’s low on fuel. That’s why race cars carry as little fuel as possible, stretching range and bolstering acceleration.

Today, it’s good to be a lightweight.