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Does driving 55 mph help me save gas?

 

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Question:

With the high gas prices, I have been wondering if driving 55 mph would help me save gasoline. What is your experience?

Answer:

With any automotive vehicle I have driven, driving 55 mph would save gas. But what are the implications on driving time?

I will look into 2 scenarios here: the daily commute and a long road trip.

Saving Gas on the Daily Commute

I personally have a long commute to work. 48 miles (77 km) each way. My commute starts with 0.8 mile residential road, then 46.5 miles highway and 0.7 mile slow industrial road. A total of 3 stop lights. About 20 miles of the highway portion are a curvy mountain pass (2 lanes each direction) where the speed limit is 50 mph (80 km/h). The remaining highway portion of my commute has a speed limit of 65 mph (104 km/h).

If I drive during heavy traffic, which means any time between 6am and 9am, and I go with the flow of traffic, then this trip will take me 75 to 80 minutes, assuming there are no accidents.

If I drive off-hours, and maintain 65 mph (which constitutes speeding on the 20 mile stretch where the limit is 50), then I can make it in 55 minutes.

At night with very little traffic I was able to do this 48 mile trip in 44 minutes, driving a Pontiac Firebird. With my Mazda RX-8 I was able to shave off another 2 minutes, bringing it down to 42 minutes.
This meant some serious speeding - think 100 - 120 mph in 65 zones and 100 mph on the mountain pass which is officially limited to 50). In theory, if one drives 100 mph, it should take only 30 minutes. However, even at 1 in the morning, every now and then you will either see a police car parked on the side or some slow drivers blocking all lanes. I have to switch freeways 3 times on each trip, and that's where other drivers always slow me down to something like 40 mph. I may have just gained a full minute by speeding but now, being stuck on the on-ramp, I lose it again.
I used to be pretty bad. I got 4 tickets in 24 months. At that point, I decided to buy a commuter car, a 1992 Ford Festiva (see picture on the left) for $450.
I bought this car because I was tired of getting tickets and having to drive a modern car at less than half of its potential speed. I was tired of being stuck behind slow drivers.
With the Ford Festiva, I rarely find a driver slower than me (they do exist - SUV drivers on cell phones!). As a result, I have a more relaxed drive.


So how much gas does it cost to drive my 96 mile commute? Let's assume a Gallon of gas is $2.50
- Speeding as if I had stolen the car (RX-8):
Fuel economy will be down to 19 mpg then.
96 miles / 19mpg * $2.50 = $12.63
85 minutes (best time)

- Following traffic, in the RX-8 (65 mph)
This car gets about 22 mpg if you drive it like grandma,
basically following flow of traffic and so on.
96 miles / 22mpg * $2.50 = $10.90 to drive to work.
100 minutes travel time.

- Driving 55 mph in the RX-8
Now the RX-8 will get 24 mpg.
96 miles / 24mpg * $2.50 = $10.00.
104 minutes travel time.

- Using the commuter beater car (Ford Festiva).
Average fuel economy in that vehicle with manual 5sp transmission
is 44 mpg, at speeds between 55 and 65 mph.
96 miles / 44mpg * $2.50 = $5.45
104 minutes travel time.
(Note: the travel times are estimates. Obviously one does not drive on a perfect track but has to vary speeds)

So the savings in gasoline are not to significant. Driving 55 mph instead of 65 will not cost you much time. It would save me 90 cents a day. Probably there are other savings for example less wear on the brakes and tires.

Is it worth it to speed at all? Not when you look at the numbers. Certainly it gives some thrill and satisfaction to just fly by SUVs or overly heavy muscle cars (think: Trans Am, Ford Mustang GT) that have to slow down in curves, but it saves 13 minutes. Assuming that you did not get caught by the cops and you did not get into an accident which in my opinion is more likely if you speed like that - how will you make use of those 13 minutes? Will you turn on the TV and watch commercials?

I have concluded that it is best for me to drive the Ford Festiva with its measly 63 hp engine - saves me about $5 in gasoline and its tires are a lot cheaper also. In fact the whole car cost me less than 2 tires on my sports car.

Saving Gas on the Long Road Trip

Last month I drove to Las Vegas. That's a distance of 530 miles from the San Francisco Bay Area (where I live). I could've done this trip in the little gas saver car - at 44 mpg I would have paid $60 in gas money. (1060 / 44 * 2.50 = $60)
I chose the RX-8 instead and paid a little over $120 in gas money.

Yes, on a long road trip with decent traffic situations, you can save serious time if you speed.
It took me 7h to drive to Vegas (with some breaks included). In the Festiva it would probably have been 9h. I was willing to pay $60 more to save 2 hours of my time in each direction.




Comments:

You are on page 1 of 2, other pages: [1] 2
2006-02-24, 13:30:04
anonymous from United States  
rating
A couple of tiny errors:
1 Trans Am is two words.
2 Every car must slow down for corners. Even a Lotus.
Otherwise, very good info.
2006-03-08, 03:40:10
anonymous from Singapore  
2 Every car must slow down for corners. Even a Lotus.

Yes, but MPVs have to slow down MORE.
2006-04-16, 08:43:14
anonymous from United States  
Maybe this should be a comparison in your Mpg Mph factor/ratio


Keywords: oldtimer car
2006-08-29, 13:01:29
anonymous from United States  
rating
over a 2000 mile trip which i made twice in six months, at 55 mph i got 28.5 mpg in my 92 plymouth voyager. At 65-70 mph i got 23. About the same a/c use and load.

5.5 mpg for slowing down.

i got 30 mpg lasy year going 50 from tucson to wichita, ks.
2006-08-29, 14:43:29
anonymous from United States  
rating
- Driving 55 mph in the RX-8
Now the RX-8 will get 24 mpg.
96 miles / 24mpg * $2.50 = $10.00.
60 minutes travel time.

I'd like to know how you went 96 miles in one hour at 55 miles per hour- None of your calculations add up. Or are these cars sporting a super-secretive technology that morphs time...
2006-08-29, 15:16:22
Peter (author) from United States  
to anonymous:
I made a mistake. Copied and pasted those paragraphs and forgot to calculate the proper travel time. I corrected it now.

The original article said '42 minutes (best time)'.
That was going one way. I made it an 85 minutes for roundtrip now.

Now at a speed of 65 mph. In theory the 96 miles should take 88 minutes, but you have to slow down a few times. Traffic lights. Stop signs. It comes more to 100 minutes.

If you go 55 mph, then it is nearly the same - 104 minutes I post now.
2006-08-29, 18:46:05
anonymous from United States  
Very good then ;)
2006-09-05, 14:18:04
anonymous from United States  
Has anyone figures on what the U.S. could save on gas if we had a new 55 mph law again?
berkleys@fast.net
2007-11-08, 13:41:44
anonymous  
rating
this is retarded. the faster you go, the more gas you use.
2008-01-31, 14:14:15
anonymous from Redondo Beach, United States  
To respond to the comment about saving gas in the nation by implementing a 55mph law. That would be silly. The speed limit should be regulated by flow of traffic and a max top speed.
In CA people drive in freeways at 80 mph, 85mph, flow traffic. That is a safe speed dictaded by safe conditions and judicious drivers. A 55 mph limit only enriches the police and the state in uncalled for fines, and does nothing to reduce consumption, which in fact is due to american way of life, the selfich burning of massive amounts of fuel by single drivers steering SUV vehicles with gargantuan V8 and V6 cylinder engines.
The reality is the country is not moving on to smaller engines and efficient ones because in doing so, the big 3 US automakers would dissappear of the face of the planet, because these 3 companies are terrible tecnology wise ( Chrysler doing better since Mercedez Benz owned it, but MB is selling it due to lack of profit ) and these 3 companies can only build big engines efficiently ( power wise ) but terrible mileage gargantuan guzzlers.
It is either the US ditches off it's 3 automakers into oblivion, and buys imporeted vehicles ( redirecting american investment into other areas were US is good ) or else stubbornly we keep these 3 sinking boats afloat at constituents' expense, and die adamant and stubborn without any hope ( just prolonging the agony of the US automakers and draging along the american constituent.

___Ja. ________________________________________________________________________-
2008-04-06, 17:24:50
anonymous from United States  
We could seriously reduce our dependence on foreign oil TOMORROW by driving 55. It doesn't require any new technology. Anyone can do it. It just takes a change in behavior. By the way, the difference in fuel consumption between 72 and 55 in my Subaru Impreza is about 1/3. Since we get about 1/3 of our oil from the middle east, I have eliminated my dependence on mideast oil by driving 55. You can cut back your use of foreign oil and reduce your carbon footprint TOMORROW by changing your behavior. Do it for your country!

Don't listen to me or any other idiot on this page telling you what is real and what is not. Test it out for yourself.
2008-05-23, 21:22:36
that_it_gal@yahoo.com from United States  
i have a 05 navigator..mind you i have 6 kids.wanted a fancy car for myself and for work when showing clients property. yes, the gas is killing me now(luckily i dont drive more than 15 miles a day) however over the past year prior to the crazy gas wallet robber,i had been doing lots of research on oil companies and listening alot about carbon footprint.
as of today i feel horrible with my gas guzzling beast of a machine.as beautiful as it is i just know there is no room in this world anymore for these types of cars.i know with me having 6 kids ive left a big enough carbon foot print already..but im happy to say outside of my obsession for my navigator..we are a pretty mindful family.we grow some veggies working on fruit,we recycle,buy only what we need,watch our energy use closely,saving to solar outfit our home,we dont eat alot of red meat,conserve water,and many other things.i guess my choice of cars is my final habit i need to work on.
so as of now i cant dump the navi for money reasons. but i will only drive it from now at 55mph when i do decide to drive it.i will be parking it in my garage and will start driving my suburban that gets way better gas mileage.my husband has bought a 4cyl for work and as soon as we can we will trade the gas guzzlers for a hybrid thaoe.so i want to change and this navi driver will change her driving ways.
2008-06-02, 02:53:47
anonymous from United States  
So anon, on his 2000 mile trip, saved about $50 and lost about 7 hours.

If your time is that worthless, then enjoy your 55 mph drive. Just stay in the right lane.




2008-06-03, 08:21:09
anonymous from United States  
rating
I have an 07 Dodge Nitro 4x4 and make a 15 mile trip each way to work and home every day (10 miles each way are on the highway). When driving 75 mph on the highway and posted speed limits in town the vehicle averages around 17 miles to the gallon. I have slowed down to 55 mph on the highway and the last time I filled up I was astonished to see that the Nitro got about 26 miles per gallon. It is a significant savings and well worth the extra time it takes. I have noticed it also helps with road rage, at least on my end.
2008-06-22, 17:47:49
anonymous  
Just more insane people on here. Are you people crazy driving at those high speeds. What is your point driving fast if you know others are driving the speed limit. That really makes me want to be a cop reading these stupid blogs.
You are on page 1 of 2, other pages: [1] 2

 

 

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