We don't need hybrids,.. we need 55MPH! - a long winded ramble.

[edro]

Inflating to sidewall should be law too!

 

[NutBucket]

Really? Once a week I have to drive from DC to Annapolis and I average 70-80 MPH the whole way there and my MPG is at it's absolute best on these trips.

Could it also be because its a sustained bit of highway driving without much acceleration?

Also, try the same route going 55 and report back. Chances are you'll get better mileage.

I've observed similar gains to the OP in all my cars. Even the little CR-Z gets much better fuel economy at 55-60 than 70-75.

 

[Analog]

You're stating the obvious.

That being said, you are putting the burden of saving energy on the consumer, as in its your fault that we're in the energy crisis we're in. The government needs to regulate your speed, because your too stupid to figure that out yourself. You have just proven the point that by self regulation, you can save almost 30% in fuel. Now, if I said that I have a widget that will increase your mileage by 30%, I bet I could sell a bunch of them. You did it for free.

Now explain to me the following points:

• All the major car makers have diesel vehicles that are sold in Europe that get significantly better fuel economy, but choose not to sell them here. Why doesn't the government mandate this?
• Since 1985, horsepower in the new vehicle fleet by the car makers has essentially doubled, yet the fuel economy has remained relatively flat. If the horsepower of cars were the same average as back in 1985, the fleet's fuel economy would almost double. I'll give you a personal example. When I was shopping for a new car in 2009, I was very interested in the Honda Fit. It got great gas mileage. In my due diligence, I found out that the Fit that was sold in Japan had an engine option that had reduced horsepower, yet had significantly higher fuel economy - yet you couldn't buy it here in the US. Don't tell me that the car makers need to design new engines.. Why doesn't the government mandate this?
• Since 1985, cars have become heavier, which reduces fuel economy. Part of this is because of the greater number of features cars have today (like certain safety equipment), but reducing weight is a player in fuel economy, but it seems to evade the radar on energy consumption. Why doesn't the government mandate this?

The bottom line is the government doesn't need to burden the consumer with another failed regulation - you can reduce your speed on your own. But as a consumer, I should have the choices I've outlined above - and I would much rather have the government regulate THAT. :|


that's my 2 cents..

 

[Red Storm]

Could it also be because its a sustained bit of highway driving without much acceleration?

Also, try the same route going 55 and report back. Chances are you'll get better mileage.

I've observed similar gains to the OP in all my cars. Even the little CR-Z gets much better fuel economy at 55-60 than 70-75.

Yes that's probably it. At 55 I can't do that though, so my foot would always be on the pedal. At ~70 I can cruise and this saves me gas.

So for me, in real world usage driving at >55 is more fuel efficient than at 55.

 

[JoLLyRoGer]

I hope you realize that the number one influence on the prime range for fuel efficiency for a vehicle is the differential ratio. If you were to restore your differential to stock (3.73?) you would probably see the speed at which you drive for best fuel efficiency rise to 65 mph.

Oh I full well understand this. The car had 3.30's in it originally and would do 22-23 MPG's at the higher speeds. However that's not to say it wouldn't do 26-28 at slower speeds either. I never build this car to be fuel efficient (as indicated in the OP). I'm just making conversation about it.

And I'll also concede that one specific finding shouldn't drive national policy as others have suggested. But, all in all I think it's worth a second look.

 

[FoBoT]

Inflating to sidewall should be law too!

yes, in a perfect Utopian totalitarian global world state, that'll be the way it is. i want to be a tire inspector and pass out tickets for under inflated tires :|

 

[gorcorps]

A few things wrong with what you're saying.

First, every car will have a different "sweet spot" because every car will have different aerodynamics. 55mph is not the best for everyone so everybody should be able to find their own sweet spot.

Second, it's not the govs place to force my vehicle into the most efficient range. If I want to fly by at a gas guzzling 85 then that's my own fucking decision. It's my money and if I want to spend a bunch on gas then it's my choice. Forcing everybody to go at a more reliable speed is one of the most asinine things I've heard in a while, as there's nothing stopping you from going 55 on a 70 to be efficient. You're happy because you're saving gas, and I'm happy because I can get home faster at the expense of MY OWN FUCKING MONEY. Forcing it down just pisses people off, and the slow drivers get no other perk than they would by driving slower anyway.

Third, your post makes it sound like you just now found out about this by yourself. Have you never heard about this before? It's so well known that even the mythbusters covered it years ago. A lot of us know our cars aren't as efficient at 70+ but we really don't care.

 

[dank69]

If you are worried about gas money you are doing it wrong.

 

[IronWing]

A few things wrong with what you're saying.

First, every car will have a different "sweet spot" because every car will have different aerodynamics. 55mph is not the best for everyone so everybody should be able to find their own sweet spot.

Second, it's not the govs place to force my vehicle into the most efficient range. If I want to fly by at a gas guzzling 85 then that's my own fucking decision. It's my money and if I want to spend a bunch on gas then it's my choice. Forcing everybody to go at a more reliable speed is one of the most asinine things I've heard in a while, as there's nothing stopping you from going 55 on a 70 to be efficient. You're happy because you're saving gas, and I'm happy because I can get home faster at the expense of MY OWN FUCKING MONEY. Forcing it down just pisses people off, and the slow drivers get no other perk than they would by driving slower anyway.

Third, your post makes it sound like you just now found out about this by yourself. Have you never heard about this before? It's so well known that even the mythbusters covered it years ago. A lot of us know our cars aren't as efficient at 70+ but we really don't care.

I award one cookie for the best Spidey impression in a non-Spidey post.

 

[LTC8K6]

500 mile trip at 55mph = ~9 hours
500 mile trip at 75mph = ~6.5hours

Enough said.

BTW, I-95 certainly wasn't built for 85mph.

I-40 in Eastern NC on the other hand...

 

[ViviTheMage]

haha, when I bought my 2.0L golf...the license plate said 55MPH on it, haha. ripped it right off, time to throw a turbo on it

 

[CPA]

On a trip to Nawlins from Houston, I averaged over 41mpg in my Honda Civic Hybrid going on average 77mph. On my daily commute, averaging about 70mph, I get about 35mpg. I think we should increase speed limits for hybrids.

 

[LTC8K6]

You're stating the obvious.

That being said, you are putting the burden of saving energy on the consumer, as in its your fault that we're in the energy crisis we're in. The government needs to regulate your speed, because your too stupid to figure that out yourself. You have just proven the point that by self regulation, you can save almost 30% in fuel. Now, if I said that I have a widget that will increase your mileage by 30%, I bet I could sell a bunch of them. You did it for free.

Now explain to me the following points:

• All the major car makers have diesel vehicles that are sold in Europe that get significantly better fuel economy, but choose not to sell them here. Why doesn't the government mandate this?
• Since 1985, horsepower in the new vehicle fleet by the car makers has essentially doubled, yet the fuel economy has remained relatively flat. If the horsepower of cars were the same average as back in 1985, the fleet's fuel economy would almost double. I'll give you a personal example. When I was shopping for a new car in 2009, I was very interested in the Honda Fit. It got great gas mileage. In my due diligence, I found out that the Fit that was sold in Japan had an engine option that had reduced horsepower, yet had significantly higher fuel economy - yet you couldn't buy it here in the US. Don't tell me that the car makers need to design new engines.. Why doesn't the government mandate this?
• Since 1985, cars have become heavier, which reduces fuel economy. Part of this is because of the greater number of features cars have today (like certain safety equipment), but reducing weight is a player in fuel economy, but it seems to evade the radar on energy consumption. Why doesn't the government mandate this?

The bottom line is the government doesn't need to burden the consumer with another failed regulation - you can reduce your speed on your own. But as a consumer, I should have the choices I've outlined above - and I would much rather have the government regulate THAT. :|


that's my 2 cents..

Those modern diesels need low sulfur fuel, which only recently became available widely in the US. Diesels have until very recently, been too dirty for the US.

European cars don't seem to get that much better fuel economy than their American counterparts, unless they have diesels. And unless you forget that their gallon is significantly larger.

The weight is probably almost entirely due to government regulated safety equipment, and requirements to meet ever more stringent crash test standards. More of it is coming as well.

 

[spidey07]

My car, 2004 acrua TL manual gets worse mileage at 55 mph. Too high for 5th, too slow for 6th. Sweet spot is around 70-75 at 32mpg. Speeds below 60 and it drops into the 28-29 range.

 

[overst33r]

Nope. I use less gas going 70 instead of 55. Proven this every time. I get 18 MPG if most of my driving is 55 and I get 22 if most of my driving is 70-75.

So I invalidate yours and the OPs claim. Anecdotal evidence should not make a national policy. If you feel like driving 55 on a 70 highway, then feel free. Just stay out of the left hand lane because that's where I'll be.

Well then my car is breaking the laws of physics. I get better gas mileage going 70 than I do 55.

Not saying you're wrong (even though you probably are until you provide car specs I won't say for sure), but see table 4-26. The fact is that it holds true for the majority of the cars on the road. Until that changes, 55 will yield better FE than 70.

http://cta.ornl.gov/data/tedb30/Edition30_Chapter04.pdf

 

[Train]

I swear my Wife's 200 gets higher MPG at 65 than at 55, if we are driving across the state, I put it at 65-70 and cruise. 55 is too damn slow

 

[Red Storm]

Not saying you're wrong (even though you probably are until you provide car specs I won't say for sure), but see table 4-26.

http://cta.ornl.gov/data/tedb30/Edition30_Chapter04.pdf

See my other post. On paper data charts are assuming (I'm assuming) that your foot is always on the gas. I have to do that when going 55, but not when I'm going ~70. So in the real world, I'm saving gas.

(2011 Altima 2.5)

 

[zinfamous]

55 MPH is fine on roads with a 55 MPG speed limit. Stay out of the left lane on the interstate.

I want one of those cars

 

[manimal]

I think everyones mileage numbers are skewed. I get about 16 mpg on my G35x. If your not WOT ALOT your doing it wrong.

 

[LTC8K6]

Not saying you're wrong (even though you probably are until you provide car specs I won't say for sure), but see table 4-26. The fact is that it holds true for the majority of the cars on the road. Until that changes, 55 will yield better FE than 70.

http://cta.ornl.gov/data/tedb30/Edition30_Chapter04.pdf

1997 was a long time ago, and several of those cars were from well before then.

Cars now routinely have 5 or 6 or even 8 speed transmissions, and much more fuel efficient engines, and probably much more aerodynamic bodies as well.

 

[DaWhim]

we don't need a speed limit! if you want to drive at 55mph, just drive it on the right side on the road and get the hell outta my left lane.

 

[ShawnD1]

So from your one test with a car far outside the average and you think national policy should be based on it?

Slower driving getting better gas mileage is a generally accepted fact. A few simple things about fuel economy:
-drivetrain drag is less when using higher gears (a car in first gears slows down extremely fast even without hitting the brakes)
-drivetrain drag is less at lower rpm
-aerodynamic drag is less at lower speeds, and it increases by the square of the vehicle's velocity (2x as fast = 4x as much drag)

When all of these rules are put together, you get one universal way of getting the best gas mileage:
You will get the best mileage when driving in the highest gear at the lowest rpm. In most cars, that's somewhere around 40-50mph.

The general rule told to drivers in Canada is that your gas mileage decreases by about 10% for every 10km/h of speed increase. From my experience, that's a fairly accurate estimate. My Civic would get horrible gas mileage when driving 140km/h (88mph). It could drop by as much as 40% just by driving fast.

 

[trmiv]

No thanks.

 

[Ninjahedge]

Drag due to wind resistance goes up by the square of the velocity. that does not matter when you are going 20-30 mph, because most vehicles are aerodynamic enough that other things (like wheel friction, engine drag, etc) factor in a bit more.

But when you start getting up to 50-60 mph, it jumps up in effect quite dramatically. A good test of this is to find a nice flat stretch of highway and crank it up to 90 or so, then let off the gas and see how quickly your speed drops. 90->70 will come much quicker than 50->30.

Now, the other issue is gearing. "50mph" is NOT the most efficient for all cars. Especially manual transmissions. I used to get much better mileage by skipping up the gears a bit quicker. Cruising at 40 in 5th gear will use less than in 4th. Automatics may not let you do that easily.

As for hybrids, they do not factor in at all in highway driving. They make a difference in stop-start efficiency.

Wheat we NEED in cars now is a 200HP vehicle that gets 40mpg highway, not a 400HP vehicle that gets 20. (I see all these ads for the 500+ HP Caddies and just wonder what old fart really needs that power... IN A LUXURY VEHICLE!).

Meh, reducing the limit to 55 will do little for our situation.

Jolly, just as an experiment... try going 70, but ease off on the accelerator. Try to get out of 1st gear ASAP and get up to 5th even at slower speeds. See what a feather touch on the gas and brakes does for your mileage.

 

[fenrir]

That assumes time spent traveling is equal (hint: faster cars spend less time traveling). Cars of the past might have been at their peak gallons per mile at 55, but without looking at how the average car actually performs now you have no way of knowing what the ideal is. I'm not saying he's wrong; I'm saying his methods for determining how things should be is stupid.

WTF? How does time spent traveling have anything to do with it? If you travel 100 miles, it doesn't matter if it takes you 6 hours or 2 hours when it comes to MPG.