I’m right next to ya on this one Jeff. I’m sure most of you guy don’t want to mess with stuff like over coffee this morning. I myself sure don’t want to work it out before breakfast. In fact I bout got my fill just lookin’ all this up before the sun came up.
But basicly it says that your gonna have a LOT more problem with drag at 55 mph than ya do at 25 mph. And if you’re lucky enough to have a gear that will permit you to run at 65 mph, well, you can see the problem. About 60% of the power required to cruise at highway speeds is taken up overcoming air drag, and this increases very quickly at high speed. Therefore, a vehicle with substantially better aerodynamics will be much more fuel-efficient.
Additionally, because drag does increase with the square of speed, a somewhat lower speed can significantly improve fuel economy and reduce wind noise.
Multiplying Cd by the car's frontal area gives an index of total drag which is a commonly published rating of a car's aerodynamic smoothness, related to the shape of the car. I couldn’t find one for an Advanced Design Chevy truck but I’d say a Hummer comes close.
Wind noise example; I took the wife out for a little drive Sunday afternoon. I think 45 mph with my 4.57 gear is about where the engine feels best. We were fine going east, had a nice tail wind, but heading back home with the 30 mph head wind presented us with an air speed of 75 mph. The wind noise was such that we pretty much had to yell at each other to hear and we just shut the tunes off cuz they were about drowned out by the breeze. Drilling more holes in that pristine body, not one of my favorite things, it's just one more spot for rust to get started. And then there is the stop light thing, if its gonna be driven much at all your gonna have to hang you head out the window to see when the light turns green.
Then there is the aesthetics angle, and in my personal opinion Fulton visors, air horns on the fenders, mud flaps and coon tails on the antenna all fall into the same boat. But then again that's just my own opinion.
Denny Graham
Sandwich, IL
