Elkman
Senior Member
The OEM air filter is going to be as good or better than a K&N unless you spend a lot of time driving on dirt roads or trails. It takes power to move the truck and it takes fuel to generate that power. It also takes power to accelerate the truck and to keep it moving with most of the fuel used to overcome air drag which in turn increases with the square of the truck's speed. At 60 mph the air drag is 4 times as great as at 30 mph.
With any new truck I spend time at various speeds on the highway to find the sweet spot where it gets the highest mpg. With my diesel 2500 truck it is at 62 mph. With my gas powered full size SUV it is at 55 mph (though it is 40% greater than the heavier and far less aerodynamic diesel truck). The SUV fuel economy is anywhere from 16 mpg to 34 mpg depending on the speed and how much acceleration is done. I average 22 mpg with my own mix of driving. I do avoid being stupid and driving faster than I need to as much as possible. No need to drive at 75 mph for a 15-20 minute trip someplace.
The diesel truck's fuel economy ranges from 10 mpg when towing a camper in 20 mph winds at 65 mph to 22 mpg when driven at 62 mph with no wind and no camper. The overall mpg has averaged between 16 and 18 mpg with normal use and a mix of in town and highway driving. I avoid making short trips with the diesel truck as it is hard on the engine and hard on fuel economy. For short trips where I do not need cargo space I drive a Prius that averages 44 mpg.
There are no magical solutions to improving fuel economy, only good driving habits. The big rig drivers with the identical trucks pulling identical loads on the same route can get 8 mpg or 10 mpg and the difference is 100% with the drivers. Freightliner and the other truck manufacturers are trying to use smarter engine and transmission control systems to turn more 8 mpg drivers into 10 mpg ones but these systems can only do so much to compensate for the skill and intelligence of the driver.
With any new truck I spend time at various speeds on the highway to find the sweet spot where it gets the highest mpg. With my diesel 2500 truck it is at 62 mph. With my gas powered full size SUV it is at 55 mph (though it is 40% greater than the heavier and far less aerodynamic diesel truck). The SUV fuel economy is anywhere from 16 mpg to 34 mpg depending on the speed and how much acceleration is done. I average 22 mpg with my own mix of driving. I do avoid being stupid and driving faster than I need to as much as possible. No need to drive at 75 mph for a 15-20 minute trip someplace.
The diesel truck's fuel economy ranges from 10 mpg when towing a camper in 20 mph winds at 65 mph to 22 mpg when driven at 62 mph with no wind and no camper. The overall mpg has averaged between 16 and 18 mpg with normal use and a mix of in town and highway driving. I avoid making short trips with the diesel truck as it is hard on the engine and hard on fuel economy. For short trips where I do not need cargo space I drive a Prius that averages 44 mpg.
There are no magical solutions to improving fuel economy, only good driving habits. The big rig drivers with the identical trucks pulling identical loads on the same route can get 8 mpg or 10 mpg and the difference is 100% with the drivers. Freightliner and the other truck manufacturers are trying to use smarter engine and transmission control systems to turn more 8 mpg drivers into 10 mpg ones but these systems can only do so much to compensate for the skill and intelligence of the driver.