This graph is fairly universal, a car with bad aerodynamics might have a steeper fall-off slope after 55MPH, and one with great aerodynamics might have a shallower fall-off, but 55 is roughly the point at which aerodynamic drag begins to exert itself and become the primary toll on fuel efficiency. On the lower speed side of the graph, the car is overcoming the rolling resistance of the tires, as well as the lower gearing of the transmission and the final drive, so, again, the slope may be more shallow or more steep, but the switchover from rolling resistance to aerodynamic drag is roughly consistent around 55MPH. This has everything to do with the infamous "double-nickel" speed limit of the 1970s and 1980s, and stands true even today.
Depends on the car but as you go faster there is more drag on the car from air resistance.. You must be in the optimum RPM range to get the best gas mileage. I would say if you cruised for 10 miles at 40 mph your would get better MPGs than going that distance at 55mph but how much less time is the car running ect.. There are alot of variables.. I have a tuning devise that tells me how much fuel i use per revolution of the engine.. Its pretty sick and i get the best mpg cruising at 67...
It obviously depends on the vehicle, but it can be significant. I get about 18 mpg in my truck at 55 mph. But if I cruise at 75 mph, it goes down to about 12 mpg. Some of this can be explained by the engine not operating in it's "sweet spot." But the majority is due to additional wind drag. Bottom line...cruise slow and save gas. Good luck.
I actually get better gasmilage doin 70 than i get at 55, but my engine was custom biult for high RPM usage... at 70 i,v gotten up to 35.8 at 55 I'v gotten up to 26 somathin...
It all depends on what your driving... and one of them on board computers that calculate your gasmilage helps alot too!!!
Answers & Comments
Verified answer
See the graph part way down this page:
http://www.fueleconomy.gov/feg/driveHabits.shtml
This graph is fairly universal, a car with bad aerodynamics might have a steeper fall-off slope after 55MPH, and one with great aerodynamics might have a shallower fall-off, but 55 is roughly the point at which aerodynamic drag begins to exert itself and become the primary toll on fuel efficiency. On the lower speed side of the graph, the car is overcoming the rolling resistance of the tires, as well as the lower gearing of the transmission and the final drive, so, again, the slope may be more shallow or more steep, but the switchover from rolling resistance to aerodynamic drag is roughly consistent around 55MPH. This has everything to do with the infamous "double-nickel" speed limit of the 1970s and 1980s, and stands true even today.
Depends on the car but as you go faster there is more drag on the car from air resistance.. You must be in the optimum RPM range to get the best gas mileage. I would say if you cruised for 10 miles at 40 mph your would get better MPGs than going that distance at 55mph but how much less time is the car running ect.. There are alot of variables.. I have a tuning devise that tells me how much fuel i use per revolution of the engine.. Its pretty sick and i get the best mpg cruising at 67...
It obviously depends on the vehicle, but it can be significant. I get about 18 mpg in my truck at 55 mph. But if I cruise at 75 mph, it goes down to about 12 mpg. Some of this can be explained by the engine not operating in it's "sweet spot." But the majority is due to additional wind drag. Bottom line...cruise slow and save gas. Good luck.
I actually get better gasmilage doin 70 than i get at 55, but my engine was custom biult for high RPM usage... at 70 i,v gotten up to 35.8 at 55 I'v gotten up to 26 somathin...
It all depends on what your driving... and one of them on board computers that calculate your gasmilage helps alot too!!!