Speeding on the highway adds a surprising amount to your fuel costs.


With gas prices rising, gas-saving advice abounds: Drive more gently, don't carry extra stuff in your trunk, combine your shopping trips.


This is all sound advice but there's one driving tip that will probably save you more gas than all the others, especially if you spend a lot of time on the highway: Slow down.


In a typical family sedan, every 10 miles per you drive over 60 is like the price of gasoline going up about54 cents a gallon. That figure will be even higher for less fuel-efficient vehicles that go fewer miles on a gallon to start with.

The reason is as clear as the air around you.


When cruising on the highway, your car will be in its highest gear with the engine humming along at relatively low rpm's. All your car needs to do is maintain its speed by overcoming the combined friction of its own moving parts, the tires on the road surface and, most of all, the air flowing around, over and under it.


Pushing air around actually takes up about 40% of a car's energy at highway speeds, according to Roger Clark, a fuel economy engineer for General Motors.


Traveling faster makes the job even harder. More air builds up in front of the vehicle, and the low pressure "hole" trailing behind gets bigger, too. Together, these create an increasing suction that tends to pull back harder and harder the faster you drive. The increase is actually exponential, meaning wind resistance rises much more steeply between 70 and 80 mph than it does between 50 and 60.


Every 10 mph faster reduces fuel economy by about 4 mpg, a figure that remains fairly constant regardless of vehicle size, Clark said. (It might seem that a larger vehicle, with more aerodynamic drag, would see more of an impact. But larger vehicles also tend to have larger, more powerful engines that can more easily cope with the added load.)


That's where that 54 cents a gallon estimate comes from. If a car gets 28 mpg at 65 mph, driving it at 75 would drop that to 24 mpg. Fuel costs over 100 miles, for example - estimated at $3.25 a gallon - would increase by $1.93, or the cost of an additional 0.6 gallons of gas. That would be like paying 54 cents a gallon more for each of the 3.6 gallons used at 65 mph. That per-gallon price difference remains constant over any distance.


Engineers at Consumer Reports magazine tested this theory by driving a Toyota Camry sedan and a Mercury Mountaineer SUV at various set cruising speeds on a stretch of flat highway. Driving the Camry at 75 mph instead of 65 dropped fuel economy from 35 mpg to 30. For the Mountaineer, fuel economy dropped from 21 to 18.


Over the course of a 400-mile road trip, the Camry driver would spend about $6.19 more on gas at the higher speed and Mountaineer driver would spend an extra $10.32.


Driving even slower, say 55 mph, could save slightly more gas. In fact, the old national 55 mph speed limit, instituted in 1974, was a response to the period's energy crisis.


It was about more than just high gas prices, though. The crisis of the time involved literal gasoline shortages due to an international embargo. Gas stations were sometimes left with none to sell, and gas sales had to be rationed. The crisis passed, but the national 55 mph speed limit stayed on the books until the law was loosened in the 1980s. It was finally dropped altogether in 1995. (The law stuck around more because of an apparent safety benefit than for fuel saving.)


Despite today's high gas prices, don't expect to see a return to the national 55 mph speed limit. The law was unpopular in its day, and higher speeds have become so institutionalized that even the Environmental Protection A

 

 

I have noticed the big rigs are going slower on the interstates lately.With the price of diesel over $4.00 it makes sense.

 

[sm=signs007.gif][sm=youreright.gif].......I can't drive 55 [sm=gears.gif]

 

Yep long trips are lot of fun in the MCSScrusing at 65 on 4 cyl I love my highway millege.

 

So are you one in the minority that is happy with your DOD?

 

[align=center] [/align][align=center][/align][align=center]LOL GP `Dave,[/align][align=center]The Beach Bum's were just read'in the MCF post[/align][align=center]and were listening to the radio, and one of the caller[/align][align=center]stated that the Fed should mandate the speed limit to 55 MPH : )[/align][align=center]The Host then played the song "I can't drive 55"
WoW, that was ironic/or a `sign : )[/align][align=center]I heard that song b-4, but never really listened to `it.[/align][align=center]I can't imagine what it would be like to only drive 55MPH[/align][align=center]on the interstate for any long distance : ([/align][align=center]That would sure be difficult, but I guess if there is going to be[/align][align=center]a shortage of fuel, or the cost does go over $5 a gal,[/align][align=center]it may return. : ( It's really affected what my next vehicle[/align][align=center]will `be : ( Thanks for the `laughs/post,[/align][align=center]from the [/align][align=center]BeachRiverBum's & `Space[/align][align=center][:-]Click & listen to below U-tube: ) [:-][/align][align=center]and name the car that's in the vid ?[/align][align=center]Oh, Turn up your Speaker's[/align][align=center]Great Burn Out's in Vid [8D][/align][align=center][/align][align=center][sm=gears.gif][/align][align=center][:-][/align][align=center]YouTube - I can't drive 55 [/align]by Sammy Hagar. I didn't rip this myself, just found it after I realized I couldn't find it here and thought I'd share for those that want it.
www.youtube.com/watch?v=CfNATuw1DRs - 84k

 

Iam very happy with DOD or AFM in my case.LOL
I think people expect it to work miracles. It is only supposed to increase yourfuel economy by6% to 8%. Doesn't sound like much right, but any saving is welcome if you ask me. I don't track the car. For the most part I don't accelerate hard. I get the ocasional run with another car but I try to keep those to a minimum. Tell you the truth I rarely do it now. I used to do it to see how the car would do against other cars. By now I know its limits. I have done a few 470 mile round trips and have had a little gas left so that is very close to 28 mpg. I think that is pretty good for a V8.

 

double post

 

Ferrari 512B Boxer Berlinetta...long name for a car huh?