Fuel prices and speed limits

[jjanders]

Originally posted by: JulesMaximus
Get the fuck out of the left lane if there are people behind you who want to go faster. It's not your place to police the roads.

If I'm going 10 or 15 mph over the posted speed limit and someone comes up behind me I'll move over and let them by when it is feasable for me to do so.

I'm not in the left lane, my hypothetical was on a TWO lane road (one lane each way)

Even if I'm in the right lane on a highway doing 65 and the left lane open, people going 80+ zoom up and tailgate me for awhile as if trying to make me speed up, then erratically zoom over to the left lane and pass me.

Seeing people in my rear view screaming obscenities is hilarious, creating stress for no reason FTL.

 

[LTC8K6]

"The fact that a larger, less aerodynamic car has a larger, more powerful engine surely isn't going to diminish the fuel-economy penalty, since that larger, more powerful engine is only more powerful because it burns more gas."

The larger engine doesn't have to work near as hard as a little 4 banger though. Witness a Corvette in 6th gear at 55mph. It's just loafing along. It has enough power to loaf along and maintain the high speeds. This is partly why it's fuel economy is surprisingly good.

The newer vettes are only turning something like 1400 revs at 65mph. Fast idle.

I believe the Viper is 1300 revs.

 

[91TTZ]

Originally posted by: LTC8K6
"The fact that a larger, less aerodynamic car has a larger, more powerful engine surely isn't going to diminish the fuel-economy penalty, since that larger, more powerful engine is only more powerful because it burns more gas."

The larger engine doesn't have to work near as hard as a little 4 banger though. Witness a Corvette in 6th gear at 55mph. It's just loafing along. It has enough power to loaf along and maintain the high speeds. This is partly why it's fuel economy is surprisingly good.

The newer vettes are only turning something like 1400 revs at 65mph. Fast idle.

I believe the Viper is 1300 revs.

The Vette mainly gets good fuel economy because it's relatively light and has a very low coefficient of drag. If you put a little 4 cylinder in it that needed to work harder it would still get good gas mileage, probably better.

 

[LTC8K6]

"The Vette mainly gets good fuel economy because it's relatively light and has a very low coefficient of drag.* If you put a little 4 cylinder in it that needed to work harder it would still get good gas mileage, probably better."

*And a six speed gearbox and an engine with a lot of reserve power at low revs at 55mph.

Sure, but that's not the point. The point is about a larger engine's ability to cope with increased drag easier. Which is what I think the article was trying to say.

 

[LTC8K6]

A good test might be the new Malibu. We will soon have the 6 speed LTZ available with a big V6 and a 4 cylinder. It would be interesting to see the FE differences at steady speeds in 6th at 55, 65, and 75 mph.

We'd have the gear ratios to consider, but I'd still like to know just how much better the 4 cylinder actually is on the highway cruising.

 

[JulesMaximus]

Originally posted by: jjanders

Originally posted by: JulesMaximus
Get the fuck out of the left lane if there are people behind you who want to go faster. It's not your place to police the roads.

If I'm going 10 or 15 mph over the posted speed limit and someone comes up behind me I'll move over and let them by when it is feasable for me to do so.

I'm not in the left lane, my hypothetical was on a TWO lane road (one lane each way)

Even if I'm in the right lane on a highway doing 65 and the left lane open, people going 80+ zoom up and tailgate me for awhile as if trying to make me speed up, then erratically zoom over to the left lane and pass me.

Seeing people in my rear view screaming obscenities is hilarious, creating stress for no reason FTL.

Well, on a single lane road, if you're going the speed limit I can't fault you at all.

 

[natto fire]

With the wide range of Cd of cars being driven today, this is quite simply a retarded idea. Why should someone that drives a Honda Insight with 5 times less frontal area, and more than half total coefficient of drag of a Hummer H2, or full size pickup drive the same cruising speed as said vehicle?

I know it will be a cold day in hell before legislation involves technical details, but this is one instance where it should be addressed. Air resistance goes up at the square of velocity, so the numbers can vary widely with how "slippery" a car is designed...

 

[exdeath]

Originally posted by: Captain Howdy
With the wide range of Cd of cars being driven today, this is quite simply a retarded idea. Why should someone that drives a Honda Insight with 5 times less frontal area, and more than half total coefficient of drag of a Hummer H2, or full size pickup drive the same cruising speed as said vehicle?

I know it will be a cold day in hell before legislation involves technical details, but this is one instance where it should be addressed. Air resistance goes up at the square of velocity, so the numbers can vary widely with how "slippery" a car is designed...

No no no! We can't accept that everyone has individual circumstances and let them do whats best for themselves on their own damn it! We need conformity to the state (as long as the states stance is the same as mine), we need to have to make 1 law that makes everyone do the same thing no matter what!!!!!! /tantrum

 

[LTC8K6]

Well, you just mandate the Cd of cars and light trucks, right?

 

[ViviTheMage]

No, it wouldn't effect fuel consumption enough to bother

 

[LTC8K6]

"No, it wouldn't effect fuel consumption enough to bother "

That's what I said.

Exactly the sort of useless law Congress would pass.

 

[JulesMaximus]

Originally posted by: exdeath

Originally posted by: Captain Howdy
With the wide range of Cd of cars being driven today, this is quite simply a retarded idea. Why should someone that drives a Honda Insight with 5 times less frontal area, and more than half total coefficient of drag of a Hummer H2, or full size pickup drive the same cruising speed as said vehicle?

I know it will be a cold day in hell before legislation involves technical details, but this is one instance where it should be addressed. Air resistance goes up at the square of velocity, so the numbers can vary widely with how "slippery" a car is designed...

No no no! We can't accept that everyone has individual circumstances and let them do whats best for themselves on their own damn it! We need conformity to the state (as long as the states stance is the same as mine), we need to have to make 1 law that makes everyone do the same thing no matter what!!!!!! /tantrum

How about we just mandate more fuel efficient cars and especially trucks/SUVs?

 

[MovingTarget]

I also tire of laws aimed at enforcing economic values, such as what is proposed here. Law to force people to save money on gas? What if someone doesn't care about gas prices? It's their money to waste. Who am I to tell you there needs to be a law that puts a ceiling on some aspect of your lifestyle so you can save money? Whether intentional or not, without being aware of it, it's a form of socialist control, forcing a lifestyle change for economic your own economic concerns. Most people will reach their own individual point where they have to make that choice on their own as free market forces shift. Everyone will have their breaking point. That doesn't mean there needs to be a law to arbitrarily bring someone else down to your level just because their breaking point is higher. Yet another form of social equalizing associated with socialism/communism.

This may be true to an extent, but it isn't as simple as an individual making a choice about what they are willing to pay for gasoline (by driving syle, vehicle type, whatever). I guess I'll pay devil's advocate here. There IS a communal aspect to this as a direct result of the "free market". When one person, or group of people makes a unilateral decision to waste fuel, it doesn't just impact their own pocketbook. It increases the overall demand/use of fuel, thus causing the market to raise prices. Thus, those who drive more sensibly or deliberately choose to drive more efficient vehicles will be affected. Taken on an individual basis, the effect isn't very significant, but the net affect is rather substantiative.

 

[charrison]

On my last tank of gas I made a strong effort to keep my speed between 60-65 instead of my normal 75-80 on my daily commute. Also made an effort to accelerate while keeping rpms under 2k. On the highway my rpms stayed at about 2.2k instead of 2.6k. I expected to get much better fuel economy, but it was only slightly better than my last tank at 24mpg. I will run it like this again for another tank and see if the results are the same, otherwise any savings is not worth the extra time on the road. This car is rated at 19/25 and my driving mix is 40/60.

I will note that I am actually amazed I can do 65 on the highway and not get run over. The high gas prices appear to have everyone slowing down.

 

[BUTCH1]

Originally posted by: LTC8K6
A good test might be the new Malibu. We will soon have the 6 speed LTZ available with a big V6 and a 4 cylinder. It would be interesting to see the FE differences at steady speeds in 6th at 55, 65, and 75 mph.

We'd have the gear ratios to consider, but I'd still like to know just how much better the 4 cylinder actually is on the highway cruising.

The V6 is listed @ 17/26, the four is 22/30. Although my 05 is slower than the newer model
(0-60 7.7 vs 6.6) I'm getting awesome mileage out of it, 22.6/32 and 26.8 50/50 mix. I recorded these by fuel refills not the MPG readout, not bad for a 200/228 car...

 

[RU482]

I notice now days that there is a much greater difference in speed between the slow lane and fast lane on my commute. Slow lane travels ~60-65MPH, fast lane travels 75-80MPH. used to be a pretty consistent 70-80MPH no matter the lane.

 

[jagec]

Originally posted by: LTC8K6
"The fact that a larger, less aerodynamic car has a larger, more powerful engine surely isn't going to diminish the fuel-economy penalty, since that larger, more powerful engine is only more powerful because it burns more gas."

The larger engine doesn't have to work near as hard as a little 4 banger though. Witness a Corvette in 6th gear at 55mph. It's just loafing along. It has enough power to loaf along and maintain the high speeds. This is partly why it's fuel economy is surprisingly good.

The larger engine works EXACTLY as hard...power output given the same frontal area, Cd, speed, and rolling resistance is IDENTICAL. The difference is that power output as a fraction of potential power output at that RPM is lower for the bigger engine. This is actually a bad thing, as engines are most efficient at WOT, BUT it means that the larger engine can be geared to a lower RPM and still produce enough power to keep the car going.

If you were to measure the power output of the Vette engine going a constant speed down the highway, and then replace its engine with a tiny engine that produced exactly that much horsepower PEAK (and geared it accordingly, of course), the 4-banger would get better mileage (running at WOT all the way).

 

[LTC8K6]

Yes, but I clearly was talking about revs.

 

[PricklyPete]

Originally posted by: JulesMaximus
I ride a motorcycle.

50+ mpg FTW!!! :thumbsup:

I've been driving a 1.9l diesel the last two months...40+ MPG with decent acceleration FTW...of course the company is covering the fuel costs so it really isn't making much difference to me.

 

[glugglug]

Need an option for "Hell no, reducing speed would just add more traffic jams, and even without the pileups it would make fuel efficiency WORSE."

 

[dpert1]

I am of the school of thought that if we are paying more for gas, we should be able to use it however we wish. Autobahn intestates ftw.

 

[rh71]

Going from 0-55 on local roads costs me the most gas. I watch the meter as it tells me a consistent 12-14mpg as I'm on the throttle on a heavy vehicle. The meter finally lets off at about 4th or 5th gear (of 6). Cruising at highway speeds gets me at least 2mpg more. This speed limit thing won't do much, if anything, for me.

 

[glugglug]

Originally posted by: mariok2006
It depends on the cars gearing as well. For example, cars with tall overdrive gears might like 65mph moreso than 55-60mph. You will hear people claiming they get the best mileage at 80mph, which honestly I think is far fetched if you do simple math, but people swear by it.

In my first car (an '83 Bonneville Brougham), optimum fuel efficiency was around 110mph, where it got 27-28mpg. At 55 the car would probably still be in 1st gear, and I'd be lucky to break into the teens mpg. City mileage was single digits, sometimes < 1.

 

[BUTCH1]

Originally posted by: glugglug

Originally posted by: mariok2006
It depends on the cars gearing as well. For example, cars with tall overdrive gears might like 65mph moreso than 55-60mph. You will hear people claiming they get the best mileage at 80mph, which honestly I think is far fetched if you do simple math, but people swear by it.

In my first car (an '83 Bonneville Brougham), optimum fuel efficiency was around 110mph, where it got 27-28mpg. At 55 the car would probably still be in 1st gear, and I'd be lucky to break into the teens mpg. City mileage was single digits, sometimes < 1.

Really!, did you install a jet engine on it??

 

[P0pinjay]

Fifty-five...

nah, how bout Schfifty Five...