For years,the Federal Government and the US Department of Transportation have been setting fuel economy goals for the automotive industry. These goals or standards are known as Corporate Average Fuel Economy standards, or CAFÉ ratings. The latest challenge is CAFÉ 2025 which sets average expected mileage at 54.5 miles per gallon for each automaker by the year 2025. This is an average of every vehicle the automaker produces. It includes light trucks and passenger vehicles together. In the US, we love our pick-up trucks. With that being said, in order to offset the less than average mileage on a pick-up truck, (say 48 MPG), we will likely need to see passenger vehicles averaging around 62MPG in order to gain an average fleet total of 54.5MPG. The graph highlights these goals as well as actual performance to the goals. These 2025 CAFÉ ratings are causing a monumental shift in the way we engineer vehicles.
Let’s first understand the biggest thief of fuel economy. It’s not mass, aerodynamics, or engine displacement. While they are all significant contributors, the biggest thief is what is collectively called “rolling resistance”. It is made up of the transmission, drive-shaft, and tires. Yes, your tires. Tires are made to create friction, and grip the road. It’s rather important that when you turn the steering wheel, the car turns with it. We need friction. Friction reduces MPG. Do you see the dilemma?
The automotive landscape is changing rapidly and dramatically. Hybrids, electrics, diesels, biodiesels, CNG (Compressed Natural Gas), even hydrogen powered vehicles are being evaluated as options to improve fuel economy. Do you remember the 3 in the tree transmission? Automakers are now offering 8 and 9 speed transmissions all in the name of improved fuel economy. Ford is releasing the next generation F-150 with aluminum body panels. Going from steel body panels to aluminum body panels will shed hundreds of pounds from the F-150. The lighter vehicle requires a smaller powertrain (thus reducing even more mass), and thus requiring a smaller displacement engine which requires less fuel. The reality is that there is not just one answer to achieving 2025 fuel economy standards, it is a cross-functional concerted effort impacting every aspect of vehicle design.
The US Department of Energy states that, “a 10% savings in mass equals a 6% improvement in fuel economy”. Unfortunately the reduction of mass can cause issues with Noise, Vibration and Harshness (NVH) in the vehicle cabin.
The Watches Are Set
Creative Foam’s Engineering and Development Center is heavily engaged in developing materials and part designs to help quiet the cabin, insulate and maintain the cabin temperature, quiet the road noise from the wheel wells, floor system, trunk compartment and roof. We are doing it in less space since year over year the exterior dimensions of a vehicle are getting more rounded (less boxy) to improve aerodynamics, and at the interior cabin space is trying to remain the same or get larger if it is possible. So now we are addressing NVH and thermal issues in a space less than before with more challenges than before. Creative Foam has risen to this task with better performing materials and material combinations. (See Steve Lenda’s blog on the NVH performance of the new Acura TLX).
It has been said that the first step in solving a problem is acknowledging one exists. Not only have we acknowledged it, we are diligently working with our customers as partners in solving this next technology challenge.
Stay tuned for more updates on CAFÉ 2025. As you can see on the home page, the clock is ticking. Rest assured that everyone here at Creative Foam E&D has synchronized their watches!
Sumitted by David Dyke