Lower Speed Limits, Save Fuel? Michigan Thinks So! Will Others Follow?

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Joey D

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Out "lovely" governor who I hate with a passion and has more or less derailed anything remotely good about Michigan's economy is at it again. Now she wants to lower the speed limit in order to save fuel. Now if any of you have ever been to Michigan you should know that hardly anyone pays attention to the 70mph limit, including our police. It's not uncommon to be doing 100mph+ and going with the flow of traffic, blow past a State trooper and never have them flinch. Lowering the speed limit wouldn't do any good what-so-ever because people would still do 80-100mph on the highways and the cops still wouldn't care.

Oh and it's a perfect way to hurt tourism as well, I'm sure many of you remember 15 or so years ago when the limit was 55mph nationally and how long it took to get anywhere and what a mundane drive it was. I don't know how many of you have been to Michigan but our highways lack curves, elevation, and scenery. It's like Iowa or Kansas with less corn and variable weather.

So does driving slower save more fuel? I some how doubt it with most modern cars since they now have 5, 6, 7 or 8 gears if it's an auto and at least 5 with a manual, but now more with 6. I can see it saving more fuel if we still had 2,3, or 4 gears in our vehicles but not now. Vehicles have been designed with higher speed and fuel economy in mind for the most part now.

Here is the article:

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During a press conference in Lansing, Michigan on Wednesday, Governor Jennifer Granholm suggested that the state should consider lowering speed limit from the current 70mph. Granholm was speaking during the launch of a new state web site designed to help Michigan residents save money. The site includes a calculator that lets users determine how much money they could save by car pooling as well as a service to help match up commuters to share rides. Granholm didn't give any indication of what she thought the speed limit ought to be. It seems increasingly likely that states will start lowering speed limits in the coming months if fuel prices don't subside. On the personal side, Granholm indicated that she and her husband are both driving hybrids and she is riding a bike to the office two days a week.

Oh and good for Granholm for riding her bike and driving her hybrid. It doesn't make up for the huge limo and Yukons that follow her around in her motorcad. Maybe she should focus on bringing jobs her rather then lowering the speed limit which no one will follow anyways. All I can say is I can't drive fifty-fiiiiiivvvvvveeeee!
 
Increased speed means more drag on the car regardless of how many gears there are. The increased drag will reduce gas mileage.

That being said, I see no reason to force people to conserve. Higher gas prices are already encouraging people to conserve on their own. I could see conservation being a problem if gas was dirt cheap. How ironic that politicians would try to force conservation now, when force is not needed.
 
My car gets 32mpg at 100 mph, and 43 at 70mph. If I had another gear (for fuel conservation) im sure at 100mph I could get 37mpg.
 
Well, business related vehicles, etc., can't really conserve fuel. Whatever mileage they need to cover, where ever they have to make that delivery to, they gotta get done.

If lowering of the speed limit can actually help with the crisis, I think it's an interesting idea.

My car gets 32mpg at 100 mph, and 43 at 70mph. If I had another gear (for fuel conservation) im sure at 100mph I could get 37mpg.
I take it that it's your SEAT? :eek:
 
I'm pushing probably 3500 RPM at 75 miles per hour at 5th gear. Slowing down definitely uses less gas. Ditto Danoff, though - people are conserving anyway.
 
Less gas used = better mileage.

You will lose some drag if you tailgate cars though.
 
Yes, the 55 mph limit worked so well in the 70s, 80s, and 90s (everybody obeyed it!) that it’s a great idea to do it again. Yup, yup.
 
Less gas used = better mileage.

You will lose some drag if you tailgate cars though.

More miles also equals better "mileage".

You have to take into account both the speed of the vehicle and the rate of consumption to get MPGs.
 
More miles also equals better "mileage".

You have to take into account both the speed of the vehicle and the rate of consumption to get MPGs.

Well to what I know when cars get their MPG it would be as simple as inserting only one gallon of gas and tracking how long you went when you ran out of gas.

Also don't run your car on very low gas, its bad for the car just to let everyone know.
 
How much less fuel do you use though? I mean if you are going 55mph it will take longer to get somewhere meaning the engine will have to run for a longer period. I don't know the maths but I would be curious to see how it works out. Honestly I don't think it would work out to be cost effective, especially buy the time the state replaced all the signs and had the road commision burn the fuel to go out and put them up.

I agree just let people do as they please, if your vehicle gets better mileage at 55 then go 55. I will continue just driving easy and getting good mileage at 70.
 
How much less fuel do you use though? I mean if you are going 55mph it will take longer to get somewhere meaning the engine will have to run for a longer period. I don't know the maths but I would be curious to see how it works out. Honestly I don't think it would work out to be cost effective, especially buy the time the state replaced all the signs and had the road commision burn the fuel to go out and put them up.

I agree just let people do as they please, if your vehicle gets better mileage at 55 then go 55. I will continue just driving easy and getting good mileage at 70.

The engine will probably be consuming fuel at a slower rate at 55mph, but as you said it would also have to run longer to travel the same distance. So it would consume less per say minute, but it would also have to run a longer time (more minutes). It would be interesting to see how it would effect fuel consumption, but pointless since people don't stick to the limit anyway.
 
Only Democrats drive 55.

What I hate about Jennifer Granholm is not that she's a Democrat (honest it doesn't matter what you are, politicians are crooks), but she's not ever from Michigan, let alone America. Nothing against Canadians though...except you dump all your trash in our state :grumpy:.
 
What I hate about Jennifer Granholm is not that she's a Democrat (honest it doesn't matter what you are, politicians are crooks), but she's not ever from Michigan, let alone America. Nothing against Canadians though...except you dump all your trash in our state :grumpy:.

I'm guessing there's some sort of requirement?
 
Increased speed means more drag on the car regardless of how many gears there are. The increased drag will reduce gas mileage.

That being said, I see no reason to force people to conserve. Higher gas prices are already encouraging people to conserve on their own. I could see conservation being a problem if gas was dirt cheap. How ironic that politicians would try to force conservation now, when force is not needed.

+1 on gearing

And

+1 on speed limits.

Jeezus... just like with the trans-fats... just tell people it's good for them to go slower, and they'll go slower... even better, it saves them money, which is what they want, anyway.

Forza, VW TDi engine? 43 mpg imperial is maybe, what? 38 mpg US? You could hit 50 if you drive at just 50 mph. I've done that often enough.
 
I wonder how long till someone plays the lower speed limits are safer card.
 
How ironic that politicians would try to force conservation now, when force is not needed.
Showing once again the government’s wonderful grasp of basic market economics.
 
They'd have more luck saving fuel if they set a statewide minimum speed limit of 45mph on non-residential roads. Most cars hit peak efficiency around the 40-55mph range, and there are plenty of <=35mph limited roads in this country that are unnecessarily slow. Four lanes, 20 feet of open grass on either side, nothing but businesses and commercial buildings around, 35mph? Come on.

Anyway, I'm aware of Michiganites' propensity for speed, but last I knew the average was closer to 90mph. Funny to hear you guys have broken triple digits. :lol: According to my fuel economy gauge I only get ~11mpg at those speeds; I wonder if the average american's mid-size V6 sedan does any better.

I mean if you are going 55mph it will take longer to get somewhere meaning the engine will have to run for a longer period. I don't know the maths but I would be curious to see how it works out.
Sorry to spoil your idea, Joey, but when you've already calculated the distance a car can travel on a gallon of gas, the length of time it takes to cover that distance is irrelevant.
 
I've tried it. I get 24 mpg balls out at 120 mph, 28 mpg at 80-100 mph, and 37 mpg at 40-50 mph with my 2-liter Mazda.

With the diesel, I get 38 mpg at 70 mph and I can hit over 50 mpg at 40-50 mph... but even here, where traffic is generally slower than in the US, that's a crawl compared to what else is on the road.

The math always works out the same. You have the engine on longer when you're going slower, but as long as you're doing less rpm and less actual work, you're using less gas. That is, unless your engine is tuned to run a bit rich at low rpms (possible with some carb'd engines or early generation EFis, where the car starts to lean out at high rpms).
 
I think they should lower the motorway speed limit here in the UK to 55MPH (apparently the most fuel efficient speed)....

Since the cruch I have been trying to go that slow most of the time but its really hard what with crazy people bombing along at 120 and wondering why its costing them so much to fill up...

Also my Corsa starts to really whine at anything over 60MPH because the gear ratios are too low... it really needs a sixth gear (the new D version has)...

Yeah 55 is low but if you leave plenty of time you can get to your destination ok and you will have saved like double the amount of petrol.

Robin
 
I think they should lower the motorway speed limit here in the UK to 55MPH (apparently the most fuel efficient speed)....

Since the cruch I have been trying to go that slow most of the time but its really hard what with crazy people bombing along at 120 and wondering why its costing them so much to fill up...

Also my Corsa starts to really whine at anything over 60MPH because the gear ratios are too low... it really needs a sixth gear (the new D version has)...

Yeah 55 is low but if you leave plenty of time you can get to your destination ok and you will have saved like double the amount of petrol.

Robin

On the 60mph limit single-carriageway road to work, I average low 50s and return 30-32mpg.

On the 70mph limit motorways last weekend, I averaged 67mph and returned 34.2mpg. Fully loaded too.
 
I suppose it varies with the size of car and engine.. with a 1.2 Corsa with just me in the car on the motorway I get about 42 MPG going 55 most of the time..

Robin
 
It certainly does vary with the size of car and engine - remember the TG Prius/M3 test from this season's opener? At the same average speed, the M3 was the more economical car...

If anything the UK National Speed Limit needs raising to 80mph - perhaps even 85mph.
 
Since the cruch I have been trying to go that slow most of the time but its really hard what with crazy people bombing along at 120 and wondering why its costing them so much to fill up...

There's 3 lanes in most places. People doing 120 will be doing it in the outside lane. If you're doing 55 and you're on the inside lane, I don't see the problem.
 
Anyway, I'm aware of Michiganites' propensity for speed, but last I knew the average was closer to 90mph. Funny to hear you guys have broken triple digits. :lol: According to my fuel economy gauge I only get ~11mpg at those speeds; I wonder if the average american's mid-size V6 sedan does any better.

Wow I get high 30's at Michigan speeds, but most of us here have giant ass SUV's that proabably get 4mpg at 90-100mph. Honestly I don't know why they are going to bother doing this since we grew up with speed, I mean even when it was 55mph people still drove 70-80mph and the police rarely cared. Although since our wonderful governor has ruined the state financially, if they lower the speed limit they will probably write you for 1 or 2 over just to get money out of you. So lowering the speed limit to save people money in fuel will only have them pay more money in tickets and higher insurance rates...way to think that one through Granholm :rolleyes:.

She needs to think about what is best for it's people, we are a car culture here and we've learn to drive like that. Hence why people from Ohio and Indiana are rarely, if ever, welcome on our roads...Ontario plates even less so. Honestly if they dropped the limit to 55mph and enforced it, it would be the final nail for me to move out of the state because driving up north doing 55 apposed to 90 would just be awful.


Sorry to spoil your idea, Joey, but when you've already calculated the distance a car can travel on a gallon of gas, the length of time it takes to cover that distance is irrelevant.

Like I said I had no idea about the maths involved with it.
 
She needs to think about what is best for it's people, we are a car culture here and we've learn to drive like that. Hence why people from Ohio and Indiana are rarely, if ever, welcome on our roads...Ontario plates even less so. Honestly if they dropped the limit to 55mph and enforced it, it would be the final nail for me to move out of the state because driving up north doing 55 apposed to 90 would just be awful.

Much less cars with Virginia plates. I-75 through downtown Detroit is like a perpetual drag strip.

I think it's city driving that's the bigger problem, not highway driving. The constant stopping and starting is a factor, but it's the people who slam the gas when the traffic light turns green who are really wasting gas.

I do a huge amount of city driving in my wagon, and I got around 19-20 mpg in it without being an aggressive driver at all. But expensive gas has made me keep my revs as low as possible. Now, on a single tank, I can get well over 380 miles on a single tank, which is upwards of 26 mpg. I was going the same speeds, but I accelerated up to them more slowly and kept my revs below 2,500. That's an instant mileage increase of over 25%.

Not driving like maniacs on the surface roads, in my experience, is a better way to increase mileage than lowering speed limits, which people are going to ignore anyway.

It's a real shame that, as a nation, we deal with a potential crisis only after it becomes an actual crisis.
 
How ironic that politicians would try to force conservation now, when force is not needed.

Reminds me of the "energy star" stuff. Now, they are saying it "wastes" energy so don't buy stuff that has a "stand by" feature. :dopey:
 
Increased speed means more drag on the car regardless of how many gears there are. The increased drag will reduce gas mileage.

That being said, I see no reason to force people to conserve. Higher gas prices are already encouraging people to conserve on their own. I could see conservation being a problem if gas was dirt cheap. How ironic that politicians would try to force conservation now, when force is not needed.
I've heard of many people citing their best fuel mileage at 65-70mph. It's not just drag you have to consider, which obviously increases drastically the faster you go, but also the power band of the engine and what rpm and throttle percentage it operated most efficiently. When my small engine is working to keep the car at 55mph in 5th gear I'm using nearly 50% throttle at just under 3000rpm just to maintain that speed. But at 65, I'm at 3700 using about 25% throttle. If I had all the information on fuel curves and whatnot I'd whip out some math comparing the aero drag, throttle usage and rpm for both scenarios, but I don't.
 
Yup, I know my Dad notices a difference in mpg when going to work. If he doesn't go over 55mph (50 mile journey, mostly country roads) he will get 60mpg, maybe a bit over. "Normal" driving results in about 53/54mpg. Mind you, he drives an Altea, I imagine that his quite a large drag.
 
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