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Does driving 55 mph help me save gas?


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


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.

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2008-07-27, 18:55:20
[hidden] from United States  
lets hit the middle drive the posted speed limit. Save some gas, don't get rear ended, and save some time. Trucks and cars all the same speed. Enforce the speed limits. Give tickets for slow drivers using the left lane and nail those driving 2mph over the Speed limit. If you drive the speed limit now you are impeding traffick and creating a saftey hazard. 80% of all drivers drive over the speed limits now creating a safety hazard.
You only spend 25% driving on highways. The 75% of your driving is in city or suburben areas where speed limits are less but you lose 5%on your mileage due to stop and go traffick.
Leave a few minutes ealier drive speed limits, stop racing from stoplight to stoplight and jamming the brakes to stop 2 blocks ahead. You will not only save on gas but reduce the repair bills to you car.
I have 22 stop lights in 10 miles to go shopping. You will have to stop at 75% of them every trip. Your car gets 0% gas mileage each time. Contact your political representatives to improve the traffic control system in your city.
2008-08-15, 08:28:25
anonymous from United States  
I have a 90 integra with a little work done, I have a 48 mile commute as well each way which is how I found this on google. I travelled one week as fast as my little car would go averaging max speed per day at 127mph and min speed 89mph. I used 2.5 times as much gas as the following week at posted 55mph and 65mph speed limit. However the time for speed limit and obaying traffic ran between 54 - 68 minutes. Where as the fun week ran between 24-35 minutes (the 24 minutes was this morning). I lost my point and now I just want to quit my desk job and race for a living... sigh
2008-12-06, 14:53:50   (updated: 2008-12-06, 15:09:57)
anonymous from United States  
some of you are quite funny and others are really a bit too serious. Like one said The faster you go then the more you are going to lose. Well obviously to those of you who think otherwise and risk your lives as well as so much else how about someone else's life?I live near the Southeastern border of New Hampshire and yesterday I filled the tank of my ever so beautiful '89 Volvo(no car payments) LOL but really at 1.67 a gallon are you kidding me??!! I hope next week it's like a buck!! Changing the speed to 55 which was proposed by some senator or congressman IDK they are all the same to me. is preposterous because as most have mentioned on the highway or side ride the majority of people do go over the speed limit. they are still going to do that and it will give the staties more of chance to ultimately increase our insurance. If the guy wanted to save money on a trip and he had the seven hours to just relax, reflect on life and take in the beauty of the scenery around him then Kudos to him. No offense but you probably think that your microwave is too slow. So if everyone wants to make a difference then time management and going the speed limit on the highway and buying more gas efficient cars and limiting the amount of driving ie.. trying to do errands and stuff in one place or locally so you cut down on waste (recycle and don't litter what is up with that anyway didn't your parents ever teach you to clean your room why the hell do you think it's OK to throw your garbage out the window of your car?? If everyone did that we'd be living in a slum everywhere that you look around so just please think about it next time, thanx) (where did that just come from? sorry) and then maybe you'll earn extra time watching commercials, who watches commercials anyways that's when America has their head in the refrigerator or is in the bathroom or outside smoking a cig. But really we could all make such a difference so that this current global warming slows down rather speeds up because I worry about my kids kids you know? Actually I don't even want to think about that. Well I took a break from a marketing presentation I have to give on Monday night for college and I enjoyed reading everyone's comments because they are all based on the same idea but your answers are all different some more straight forward than others, but just the same enjoyable. If you got this far and want to respond or debate more about this e-mail Please no weirdos there are a trillion other websites than you can bother someone else at. Anyway Happy Holidays and remember let's put others before ourselves and that includes the earth. Keep warm it's freezing up here!! Chow Lizzy
2009-02-23, 10:08:22
anonymous from Altamonte Springs, United States  
'Crazy' driving at higher speeds, those speeds have been deemed safe and acceptable. The speed limit is set for a reason, and going 55 in a 70 zone may save you money but it puts you and everyone else on the road at great risk. If you want the 55 mph law to be put back into effect go right ahead and push for it, but it is better for everyone if the traffic is going close to the same speed. So until that time goose the squirrels a little bit more.
There is also a point at which smaller is not better. If you have 6 kids and you are the only driver are you going to make them all illegally cram into the ford festiva or are you going to make two trips. There comes a point at which it is the per unit cost (in this case the cost per mile of transporting each person) is smaller for driving a larger vehicle, such as my grand caravan, or costs the same and saves time not having to take more than one trip.
I have a 1999 Dodge Grand Caravan 3.3l v6 and I get 24.5 mpg at 75 mph on cruse control no a/c windows down, and going at 55 doesn't bring my mpg to over 25 under the same conditions. This is different for every vehicle out there based on size, power, efficiency of engine, and wind resistance, and any number of other factors. If I take 6 other people along for the ride I take 7 along for the cost of less than 10.2 cents per mile (at 2.50 per gallon), or 1.4577 cents per person per mile. Lest say for the sake of argument that the Ford Festiva does not loose mpg being loaded down with 4 people in it. The vehicle gets 44 mpg which is a cost of 5.68 cents per mile, and per person it is 1.42 cents per mile. I know that a smaller engine will have to work much harder with 4 people than 1 and if my experience with a Geo holds it may not even make it up to speed at WOT, but I can still take 7 people for almost the per person cost for taking 4, and to take the other 3 you would have to spend twice the amount of time and money to make a second trip.
Get the best vehicle for your needs. If that vehicle ends up being a van, SUV, car, truck so be it but get it for your needs not looks (I hate to see the trucks out there on the road that have never seen anything in the bed except half a dozen grocery bags). Unloaded there is no comparison, the difference between 10.2 and 5.68 is noticeable and I can see where you would want that. But is it really justified to have two vehicles. By my calculations and for my needs it would take too long to recoup my losses.
2009-06-11, 18:35:11   (updated: 2009-06-11, 18:47:54)
anonymous from United States  
Travelling by airplane is different than by car but when you compare speeds
at the same altitude, the best milage was attained by going at about 85% of full
throttle. A flight planner I wrote shows the actul difference in gallons and time
as you use various power settings for a trip. So any power setting below the
85% of full power setting was less efficient and any setting higher was also less
efficient because consumption rose at such a high rate. As you slow, you reduce the rate
of consumption on a per minute basis but now it begins to take longer to get where
you want to go. As car drivers, we have to draw the line somewhere to protect
safety. Road conditions, weather, traffic, can all have an ill effect on our
ability to get the best RATE for our cars.

Thought this might help.
2011-11-09, 00:07:38
anonymous from United States  
drive 1044 miles at 31mpg whats the average cost of fuel round trip
2013-03-04, 17:18:13
anonymous from United States  
Every vehicle will preform differently with regard to speed and MPG. Some get their best at 45 mph and some at 65 mph but many are in the 55 mph range, it all depends. If you take 'passenger miles per gallon' into account, you'll always get the best efficiency with a fully loaded car. A fully loaded SUV can beat a Miata in that regard. It all depends on how you look at it.

Keep in mind that whatever you drive, after a certain speed, your mpg will fall off due to the effect of air resistance and you car's coefficient of drag. The harder you push against the air, the harder it will push back and YOU will loose (not the air:)
2015-01-30, 00:59:16
anonymous from Japan  
Sorry, have to agree that it's unfortunate you riueqre IE to watch it, because it means I will miss it. I'm not going to download a buggy, insecure browser just to watch one video. A very significant part of internet users (half?) use non-IE browsers. It's really not that hard to be more universally interoperable. It's a shame, I'm sure it has interesting and valuable information.
2015-01-30, 01:40:53
All of the new-from-the-factory hybrid cars sold in the U.S. tyclialpy carry an 8-year / 100,000 mile warranty on the battery. In states with California-standard emissions regulations, the hybrid battery warranty is 10-years / 150,000 miles.If the battery fails during the warranty period (which is extremely rare), the carmaker has to replace it for you FREE.That's as long as you don't void the warranty by doing things like crash the car or tamper with the battery or damage it by improperly modifying the car (such as punching through the battery casing with screws when installing things like 1000-watt speakers). I own a Prius, and with a warranty like that on my car, I'm not worried. I bought mine in New Jersey, which has California-standard emissions regs, so I'm covered for 10 years / 150,000 miles.
2017-03-28, 06:05:37
Angela from Atherstone, United Kingdom  
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