No. of Recommendations: 4
Here goes my defense of Jimmy Carter again. Maybe not the best politician but he had some excellent ideas and he's a very good person. Probably too good to be a politician in Washington.

He mandated the 55 mph national speed limit for a reason. It saves gas under most circumstances. The problem, of course, is that is takes forever to get somewhere and we are all in a hurry to get somewhere.
The old rule that driving no faster than 55 mph to save on gas still works. This guy tested a Chevy Malibu, and got an average of 35 mpg. However when he went bit over 70 mph, the mileage dropped sharply -- to 25 mpg.

For every mile per hour faster than 55 mph, fuel economy drops by about 1 percent, the drop-off increases at a greater rate after 65 mph. The faster you go, the faster the fuel goes.

from the comments section:
At 11/28/2005 11:23 PM, Steve Hendry said...
I have a 2004 Corvette, at 55 MPH (I ran the test for 1 hour) I got 27 MPG. I then ran it at 75 MPH for the same amount of time, I got 28 MPG, hmmmm... why?

I then checked the RPM that my car was producing at each speed and the gearing. At 55 MPH, the transmission was in the same overdrive gear as at 75 MPH. Next I looked at the RPMs, I was at 1800 at 55 and 2100 at 75 MPH. This was the only major difference. I then looked at the power curve on my engine and saw that my main horsepower does not flatten until I hit around 2000 RPM, which is the constant power on my car.

I then looked at your Malibu and saw the curve. I would say that this is the reason that you are getting worse gas mileage at 75 vs 55. Your car is way, way underpowered. This is the same as in Europe. I have visited there dozens of times and was always amazed that I could rent an Audi A4 or Seat or whatever, and get 35 MPG at 120 KM = 75 MPH and why that was. The reason is that European cars are built for highway driving, their power curve is set as flat at higher RPMs, therefore they are more efficient at highway speeds - 110-130KM per hour, 65-80 MPH.

So, the problem again lies in auto manufacturers here - you need to get a car that is powered for the bulk that it is carrying and it has to be geared for highway speeds.
Print the post  


When Life Gives You Lemons
We all have had hardships and made poor decisions. The important thing is how we respond and grow. Read the story of a Fool who started from nothing, and looks to gain everything.
Contact Us
Contact Customer Service and other Fool departments here.
Work for Fools?
Winner of the Washingtonian great places to work, and Glassdoor #1 Company to Work For 2015! Have access to all of TMF's online and email products for FREE, and be paid for your contributions to TMF! Click the link and start your Fool career.