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Old-Larry, I know most if not all cars burn more fuel at 75 mph than 65, but 30% more? That seems rather extreme. My little Mazda gets virtually the same mileage at the two speeds. I always check my mpg with every refueling.
Catman check again. It is next to impossible for any production car (not specially built) to get better or the same mileage at the two speeds.
1. The engine is turning faster and will require more fuel.
2. A dead weight mass requires more energy as speed increases
3. As the speed increases the force required to dispelling the air around the car increases.
4. The amount of drag (void at the rear of the car) becomes greater. Anyway you slice it more energy is required to move a weight mass faster.
"For every action that is an opposite and equal reaction." The action here is going faster. We can't the escape physical forces.
My 2005 Dodge Diesel 3500 pickup gets 20mpg at 65. It falls to 12mpg at 75 mph. That's more than 30%. But again my truck and you car are not average vehicle.
People would do 100mph on I-90 when it was slick and call that reasonable speed.
That's referred to as an "outlier."
In Scottsdale, on highway 101, people regularly get ticketed for
going over 100 mph - sometimes way over 100 mph. I don't care
what you set the speed limit at, people will do that. It isn't the
same as statistical evidence that people, in general will always
tend to add 10 mph to the speed limit.
I know that when it was 55, I would go 70 using a radar detector.
When it is 65, I still go 70. When it is 75, I do 75. If it was 80,
I'd still go 75. What I would do is ALSO not statistically valid.
Quote:
Originally Posted by rybert
... Peak Oil ...
My philosophy on Peak Oil is that as soon as we hit it and the supply drops,
the price will adjust and people will use less as it gets more expensive. Until
then, I don't care what anybody does with the gasoline or diesel that they
buy. It's too stressful to worry about that crap.
As the dollar drops in value ( with Euro now ) the price will also go up.
I would like to drive a small, nimble, fuel-efficient car, but I drive a large
and powerful sedan to compensate for all the ridiculous Hummers and
Expeditions and such on the road.
As long as someone isn't weaving in around cars and running up on people's
bumpers, I don't care how fast anyone goes on the highway. I just don't.
rybert - IIRC the ill fated 55 mph limit was just that - ill fated. it was ignored by most everybody and the right wing grabbed it as an annoying example of the "nanny" state.
Yep, and, most newer, say 10 years or younger, vehicles, get their best MPG at around 70 MPH. The real culprit when it comes to wasting gas is stop-and-go/heavy traffic. Lowering the speed limits on the interstates do absolutely nothing to address this.
... most newer, say 10 years or younger, vehicles,
get their best MPG at around 70 MPH.
Urban legend.
Not true.
See post #41 by Old-Larry for some of the reasons.
The reason this myth got started is newer cars have 5 to 7 forward
gears. Therefore, the top cruising gear is so low that at 70 mph, the
engine on a V6 or V8 engined car can be basically turning at idle
speed. This vastly enhances mpg via a reduction in internal engine
friction, but doesn't repeal the laws of physics in this case.
The best gas mileage is obtained around 40-45 mph.
With Texas possibly raising speed limit to 85, should NM go 80?
Well, I have made some threads here before suggesting that New Mexico should introduce some 80 mph speed limits. Well, it looks like Texas is proposing raising the speed limit to 85 mph on parts of I-10 and I-20, and to 75 mph (from 70 mph) in most of the state. Therefore, I think the topic of NM raising their speed limit to 80 should be reconsidered.
So, does anyone think NM should have some stretches of highway with 80 mph speed limits? Here are my thoughts:
I-25 through Sierra County.
I-40 between Laguna Pueblo and Unser exit in Albuquerque. I-40 from Unser to Rio Grande should be raised to 70 mph.
I-10 from Arizona border to Las Cruces.
US 70 through White Sands (the only non-interstate highway in NM with a 75 mph speed limit)
Also, I would raise U.S. 285 from Roswell to Vaughn to 75 mph.
So, with Texas possibly introducing 85 mph speed limits, I don't see a reason why shouldn't New Mexico introduce an 80 mph limit on a few stretches of highway. Does anyone have opinions?
Texas has different speed limits for trucks and for night; I think it'd be an easier sell if NM adopted that along with a higher top speed. Maybe 85 normal/75 trucks/night
Remember, the original impetus for 55 mph speed limit, among other things, was energy conservation. Somehow, I don't think the government or populace thinks we're better off for gas than we were then.
There are definitely stretches of I-25 through Sierra county where anything higher than 75 would be excessive, with steep hills and crosswinds making it not the best place to target first. There are other stretches that I'm sure would be fine. Add Doña Ana and Socorro counties to that sentiment.
Texas has different speed limits for trucks and for night; I think it'd be an easier sell if NM adopted that along with a higher top speed. Maybe 85 normal/75 trucks/night
Remember, the original impetus for 55 mph speed limit, among other things, was energy conservation. Somehow, I don't think the government or populace thinks we're better off for gas than we were then.
There are definitely stretches of I-25 through Sierra county where anything higher than 75 would be excessive, with steep hills and crosswinds making it not the best place to target first. There are other stretches that I'm sure would be fine. Add Doña Ana and Socorro counties to that sentiment.
I-25 N of Las Vegas to Raton should be 100, IMO.
Actually, Texas plans on eliminating the reduced night speed limits.
I've driven on many of the highways in the western US, including the lonely highways of western TX and eastern NM. I rarely drive above 75 mph even if there are no cars in sight and even if the legal speed limit is higher. The main reason is that higher speeds cause tires to heat up. Add in hot temperatures in the summer months and you have a high risk of tire failure
A tire blowout at 70-75 mph is not good, but you can probably stay in control of your car on a straight flat, road if you steer straight ahead and don't hit the brakes. A tire blowout at 80+ mph is worse, and the slightest wrong move could have you in a real bad, possibly deadly crash.
At night, a big reason to keep speeds below 75 mph is that you can't react fast enough to obstacles that might appear on the road. In rural areas, obviously animals will be encountered from time to time. Big animals are a big problem if you can't slow down in time. Other junk can appear on the road also - truck tire carcasses can really do some damage and scare drivers if you hit a large one directly. They are black so you don't see that tire junk lying in the road until it is right in the headlights. Wind can blow junk onto the road too. Seems like anytime I drive across I-10 around Deming or Lordsburg the wind is howling.
Well as an old run down ex cop that has checked a ton of high speed wrecks across the state I guess my answer would be NO
Mine too. Texas is all about oil consumption, so it makes some sense for them. But we will soon be driving smaller vehicles at slower speeds unless some energy miracle occurs.
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With Texas possibly raising speed limit to 85, should NM go 80?
