Driving slower saves gas?

[imported_Baloo]

Originally posted by: bignateyk
Depends on the car, but most reach there peak mileage around 55-60mph. That said, I drive closer to 80 on the freeway.

Not quire correct. If you drive on the highwayat at or near 30mph, you'll get much better fuel efficiency than at 55-60. That is a common myth that cars are tuned to get the highest fuel efficiency at certain speeds. They aren't. Above 30mph, wind resitance becomes a significant factor and fuel efficiency goes down as speed increases.

 

[91TTZ]

Originally posted by: Injury

lol... wind can affect your MPG but wind is not the cause behind the discussion here.

Ideally, you want to keep your car in the area right before it changes gears because it is runs more efficient when it's turning gears with less effort.

False. Wind resistance is by far the more important factor. You can gear a car so that it's turning 2000 rpm at 100 mph. That doesn't mean that you're going to get good gas mileage at that speed.

Also, you do NOT want to keep your car in the area right before it changes gears. An engine is most efficient when it operates at the RPM that it produces its peak torque.

 

[SparkyJJO]

about 50 is good for many cars. Keeping the RPMs lower in the highest gear possible is a good way to save gas.

 

[hanoverphist]

Originally posted by: IHateMyJob2004

Originally posted by: Scouzer
80km/h - 40-45mpg
110km/h - 34-36mpg

Pontiac G5 GT

I've done a handful of long range tests with my ext cab Chevy 1500 (4.8L V8)
55-60 mph: 21 mpg
65 mph: about 20 mpg
70 mph: still about 20 mpg
72 mph: 0.2 mpg less than 70 mph
75 mph: about 19 mpg

So, yes. People don't believe me. It's a pointless debate. The bottom line is that driving faster exponentially increases wind resistance. Don't believe me, then ask why it is easy to stand in 40 mph wind but 80 mph wind will probably knock you over. It's not twice as hard to stand now is it? Liek I said though, people are stubborn and comfortable in their ignorance.

So, why don't you people that think this is not true actually test out your own cars at 55, 65 and 75 like I have. I say what I say about driving slower improving fuel economy to be true because I've tested it out myself. I don't think, I KNOW!

ive done the same thing many times in my dodge truck. i get way better mileage at 65 than i do at 75, but if the limit is 75 ill still do 75. 10 under is a hazard when the rest of the world is passing you quickly, had a judge tell me that.

 

[hanoverphist]

Originally posted by: Kelemvor
I stopped speeding on the freeway and went from being lucky to get 300 miles between fill ups to now getting 350 (which is right around 30 mpg)

My cars is in it's top gear at 40. 45-50 is the sweet spot. Anything over that, wind resistance increases exponentially which means gas mileage decreases quickly as well.

Try it for your next tank of gas and you'll see the difference.

my truck does 75 at 2200rpm, so the mileage is pretty good (for a gas guzzling beast) but i did the same. no more 10 over, my tank range went from 320ish to 375ish. most freeways here in az are 65, and thats right around 2k rpm for me in 5th gear. i was very glad to see that increase in range, as ive been driving about 100 miles a day for the past few weeks, with another couple weeks left on this job from hell. at least i get mileage for it.

 

[Throckmorton]

Originally posted by: Injury

Originally posted by: tasmanian

Originally posted by: Summit
yes, because the higher the speed even if you are in the highest gear is causing you to have a higher rpm which means you are burning more gas.

I dont think its that. I think its that there is alot more wind so your car has to work harder. At 5th gear going 60-70ish my rpm is around 3000. While 50 they are alot higher.

lol... wind can affect your MPG but wind is not the cause behind the discussion here.

Ideally, you want to keep your car in the area right before it changes gears because it is runs more efficient when it's turning gears with less effort.

The biggest factor is air resistance. That's the only reason SUVs and pickups get much worse gas mileage than cars at highway speed

 

[91TTZ]

Originally posted by: brownzilla786

Originally posted by: PhaZe
you have practice hypermiling

http://www.cnn.com/video/#/vid...obrien.hypermiling.cnn

http://www.hypermiling.com/

thats a bit psychotic

If you turn off the car don't you lose power steering and brakes?

Yeah, that guy is a bit loony. Also, what he's doing is illegal. You can't speed around corners without braking, hold up traffic, and shut the car off while you're driving. And if he's going to those measures, what do you think the chance is that he actually stops at stop signs?

 

[91TTZ]

Originally posted by: Eli
Driving my Insight has taught me a lot about fuel economy.

I get the best fuel economy in town using the 1-2-5 shift method. And I floor it.

1st - floored to ~3,000RPM, shift, floor 2nd to desired speed, shift into 5th.

Originally posted by: gnumantsc
I tend to accelerate really slowly making sure I don't go past 2000rpms from a dead stop. I see all these other cars zoom by or try to make me go faster when the light is red. I don't give a crap that the light is red and you want me to waste my gas?

When going on a long trip I would rather drive faster than to save gas if its an hour difference that's a big difference in time but for say going to work an extra 5 minutes is no big deal.

I've found that accelerating slowly does me no favors. It's a time vs. instant mpg thing. I wonder if I could gather enough data to actually run the numbers.

When accelerating, the Insight engine uses a lot more fuel than it normally does. If it takes me say, a minute to get to my desired speed, I might only be getting 35MPG during that time.

However, if I employ the 1-2-5 shift, I will only be getting 20MPG while accelerating hard, but thats only the first 20 seconds or so of the minute. Now that I'm up to speed, I can shift into 5th, lean burn will kick in and I will get 65+MPG for the remainder of the minute.

There is no way that you'll get optimum fuel economy by flooring it.

Also, the previous poster who stays below 2000 rpm is most likely revving his engine well below the point of peak efficiency. An engine is most efficient at the RPM that it produces peak torque.

 

[Parasitic]

Originally posted by: Gothgar
fuck that shit, time is money.

100 miles @ 65mph = 1:32
100 miles @ 75mph = 1:20

You save 12 minutes off a 100-mile trip if you maintained consistently at 75mph. Factor in going on/off ramp, waiting at lights, braking to avoid drivers cruising in the fast lane, the difference is next to nothing. You're better off leaving 10 minutes earlier and cruising at 65mph than leaving 10 minutes later and having to rush it.

 

[91TTZ]

Originally posted by: Parasitic

Originally posted by: Gothgar
fuck that shit, time is money.

100 miles @ 65mph = 1:32
100 miles @ 75mph = 1:20

You save 12 minutes off a 100-mile trip if you maintained consistently at 75mph. Factor in going on/off ramp, waiting at lights, braking to avoid drivers cruising in the fast lane, the difference is next to nothing. You're better off leaving 10 minutes earlier and cruising at 65mph than leaving 10 minutes later and having to rush it.

Yeah, but if you go 88 mph you can get there yesterday.

 

[rezinn]

Originally posted by: lozina

Originally posted by: Billb2
Set the cruse on 55, and be surprised.

cruise sucks ass

it causes you to brake on downhills and rev the RPMS up on uphills

It's funny how people don't know how to use cruise control. It cannot brake.

 

[Parasitic]

Originally posted by: lozina

Originally posted by: Billb2
Set the cruse on 55, and be surprised.

cruise sucks ass

it causes you to brake on downhills and rev the RPMS up on uphills

Is your cruise control system your girlfriend/wife/grandma?

Edit: at least in my car my cruise control sets a minimum speed threshold so going downhill on cruise control is unaffected.

 

[dmcowen674]

Horse and buggy saves most amount of gas

 

[Eli]

Originally posted by: Parasitic

Originally posted by: lozina

Originally posted by: Billb2
Set the cruse on 55, and be surprised.

cruise sucks ass

it causes you to brake on downhills and rev the RPMS up on uphills

Is your cruise control system your girlfriend/wife/grandma?

Edit: at least in my car my cruise control sets a minimum speed threshold so going downhill on cruise control is unaffected.

You sure about that? Is it an older car?

Every CC system I've ever seen attempts to slow the car down, either by letting off the gas or downshifting, or both.

Think about it. If the cruise control didn't do this, you would fly down any hill you came across.. lol

 

[SampSon]

I keep it below 75mph at all times basically. I've only measured a .5 - 1mpg difference from 65mph - 75mph.
Anything above 75mph and the mileage drops noticeably, not too much to really care, but I also like to avoid speeding tickets.
I drive a stick shift as well, so that helps a bit.

I drive about 1000 miles per week and I record mpg on all of my fillups.

 

[Parasitic]

Originally posted by: Eli

Originally posted by: Parasitic

Originally posted by: lozina

Originally posted by: Billb2
Set the cruse on 55, and be surprised.

cruise sucks ass

it causes you to brake on downhills and rev the RPMS up on uphills

Is your cruise control system your girlfriend/wife/grandma?

Edit: at least in my car my cruise control sets a minimum speed threshold so going downhill on cruise control is unaffected.

You sure about that? Is it an older car?

Every CC system I've ever seen attempts to slow the car down, either by letting off the gas or downshifting, or both.

Think about it. If the cruise control didn't do this, you would fly down any hill you came across.. lol

I'm not idiotic enough to leave the cruise control on at 10% grades so I am only guessing from what I have seen.

 

[0roo0roo]

http://www.hypermiling.com/acceleration-costs-fuel.html
wtf.... its like he's assuming the tranny is some kind of magic free energy machine.

 

[wetcat007]

Accelerating slower also helps quite a bit, slamming down the gas pedal using a lot of gas

 

[Throckmorton]

Originally posted by: 91TTZ

Originally posted by: brownzilla786

Originally posted by: PhaZe
you have practice hypermiling

http://www.cnn.com/video/#/vid...obrien.hypermiling.cnn

http://www.hypermiling.com/

thats a bit psychotic

If you turn off the car don't you lose power steering and brakes?

Yeah, that guy is a bit loony. Also, what he's doing is illegal. You can't speed around corners without braking, hold up traffic, and shut the car off while you're driving. And if he's going to those measures, what do you think the chance is that he actually stops at stop signs?

He also doesnt let his engine 'warm up' at all. So first he starts it from a bizarre roll, and then he stops it 1/4 mile down the road at the stop light and does another cold start, and then another, and another, and then continues with the starting and stopping putting a lot of extra wear on his engine and starter system.

In an Accord.


Why didn't he just buy a Prius, or at the least, a Civic??

 

[spidey07]

Originally posted by: SparkyJJO
about 50 is good for many cars. Keeping the RPMs lower in the highest gear possible is a good way to save gas.

That is simply NOT true. My car LUGS at 50 in top gear and gets terrible gas mileage. That's why I get better gas mileage at 85-90.

For example a corvette gets it's best mileage at higher speed as well. You can't make blanket statements because it all depends on the motor and the gearing.

 

[spidey07]

Originally posted by: Parasitic

Originally posted by: Gothgar
fuck that shit, time is money.

100 miles @ 65mph = 1:32
100 miles @ 75mph = 1:20

You save 12 minutes off a 100-mile trip if you maintained consistently at 75mph. Factor in going on/off ramp, waiting at lights, braking to avoid drivers cruising in the fast lane, the difference is next to nothing. You're better off leaving 10 minutes earlier and cruising at 65mph than leaving 10 minutes later and having to rush it.

At 60 bucks per hour that time saved = 12 bucks. A lot better than any gas savings. Remember time literally is money.

 

[rocadelpunk]

this thread is full of people who think .9 repeating forever doesn't equal 1

 

[Parasitic]

Originally posted by: spidey07

Originally posted by: Parasitic

Originally posted by: Gothgar
fuck that shit, time is money.

100 miles @ 65mph = 1:32
100 miles @ 75mph = 1:20

You save 12 minutes off a 100-mile trip if you maintained consistently at 75mph. Factor in going on/off ramp, waiting at lights, braking to avoid drivers cruising in the fast lane, the difference is next to nothing. You're better off leaving 10 minutes earlier and cruising at 65mph than leaving 10 minutes later and having to rush it.

At 60 bucks per hour that time saved = 12 bucks. A lot better than any gas savings. Remember time literally is money.

Problem is that when you commute in traffic the time saved is never going to be 12 minutes, and that's only over a 100-mile run. For those who commute 20-30 miles a day you're looking at like 3-4 minutes? Literally getting caught at one stoplight can negate the time savings.

 

[Raduque]

The sweet spot for my truck is 2k RPM. That makes it about 67mph. That's plenty fast enough for me. I get around 16mpg now, instead of 12.

Originally posted by: Injury

I keep my speed at the limit in the right hand lane and don't give a crap what other people think. You can move your ass over if you wanna break the speed limit.

Get out of the fucking merge lane, you slow douchebag.

 

[AlienCraft]

2001 Focus SE
60 - 65 mph = 36 mpg
68 - 73 mph = 29 mpg

Daily numbers don't lie.
Quick starts and stops are the biggest gas waster.

If I really watch the starts and stops, i can get that combined mpg up to 34.

m o money mo money mo money!