Fuel Efficiency questions

[mtnjam]

So Mrs. Mtnjam and I drove down to the City of Rocks this weekend. I made it a point to drive 10mph less than the posted speed limit on 84. Pretty much set the cruise at 65mph, made it to Twin Falls on ~ 4 gallons (about 1/4 tank on the Tacoma) with a small amount of tailwind. All the while vehicles traveling 10mph more than me passed me. I couldn't help but start to think that we've seem to forgotten about the OPEC oil crisis in the 70's (not that I remember it that well I was only a few years old).

I was watching national news tonite listening to this lady complaining about how high the gas prices were (as her Cady Escalade was idling in the background) and that she had to sacrifice making trips to the supermarket, either eat or fill the tank, ya know the same story we've all been hearing.

Kind of an interesting graph:

So have we forgotten the lessons of the 70's??

[neck beard]

Good point.

The savings in fuel are undeniable. It is so simple to cut the gas bill on a freeway trip, just chill out and cruise slow. Let everyone pass you, get there in not much slower time than them as they usually just hurry to find the next slow spot anyway.

When I go fast, which I don't anymore, I would most of the time just wear my brakes out slowing down for the traffic clumps that I hist every 15 minutes or so. In the end I woke up and went slow.

It helps having a gutless car and loads of spare time, so speed isn't even needed anymore. Every now and then I do a 300km (200 mile) drive at 80kph (50 miles).

You might have to dispense with your male ego to do it.

The only problem with driving slow and is that it makes me fall asleep, where as high speed driving engages my senses and mind (I quite like it) and keeps me awake. If I want that thrill back, I'll rent a small sports bike for a day.

[Bart T]

well it's great to have the option of driving slowly to save gas, but on say a typical 350 mile drive, your 5 mpg "savings" is costing you a hell of a lot of time. at 70 mph, that trip is 5 hours, at 60 it's pushing 6. if your mileage is 30 at 60 and 25 at 70, you burn 14 gallons at the faster speed, and 11.7 by driving slower.

at $4 per gallon, you are saving just under 10 bucks. i'll take 55 minutes of not driving for that price anyday.

[neck beard]

I dont think you would be alone in that decision either, which demonstrates that fuel is still way to cheap in the States. Which is good, because its going to get a fuck load more expensive.

In Germany I would drive during the night 700km to the mountains at between 200 and 250kph, only 150 if I hit congestion. On the return trip I felt cruisy and took the whole afternoon, so I hung in the truck lane at 80kph. The fuel savings were astronomical, it became a personal challenge to do the whole return trip on one tank, which was almost possible in a VW Passat diesel.

Like I said, my propensity to go slow these days is supported by a lack of cash and surplus time. Until fuel prices force the average income earner to do the same, fuel prices are still too low.

[f2f]

at $4 per gallon, you are saving just under 10 bucks. i'll take 55 minutes of not driving for that price anyday.

therein lies the problem, really. everybody valuing an hour of their life above $10 (or whatever the savings are for today's gas prices) and keeping the consumption at today's levels will keep the prices going higher until they reach your particular threshold.

the issue isn't economical, it's socio-political. at what point does "if everybody drove slower we'll be saving 1,000,000 barrels a day" outweigh "i'll do as i please because i'm entitled to it"?

oh, and the savings scale is sliding depending on vehicle consumption: if i drive a 35mpg vehicle my "low spot" for gas consumption is around 65mph (assuming i'm not driving a monster pushing a hole through the air the size of rhode island).

[rbtree]

do a search on "hypermiling"

A few tips to improve mileage :

accelerate slowly....coast to traffic lights...turn off ignition at lights if you think you'll be stopped for >30 seconds or so...inflate tires to the max recommended pressure....keep windows up to reduce wind turbulence

coast on long downhill grades....it ain't legal to do this out of gear, but I've always done it....hell, even turn off the key sometimes.

I drove ~300 miles to see my 94 yr old mom for Mother's Day...took my time on the trip, drove 60-65 mostly, and my 4wd '95 Toyota 4 banger got 25.5 mpg......was in a hurrry to get home and got 20 mpg.....

some hypermilers draft behind a big truck, but that ain't too safe.....nor is riding the white line (if there is one) to reduce tire drag....

[The AD]

Yeah, I was thinking about this a couple weeks ago. As much as people bitch about the price of gas I haven't noticed that many people driving any slower on the freeway.

I did my part starting this week to save a little more gas. I'm now working from home on Mondays in addition to the Fridays I've been working from home the last couple years. Even though my company has been encouraging virtual work the last couple years I still feel like plenty of people think when you work from home you're just sort of dicking around.

[Crock]

So we lower the speed limit to 55mph. This will create better fuel efficiency in general, and for all those who choose to not obey the speed limit, the police will generate tons of revenue for the state by writing tickets. Simple solution that should be seriously considered. Swallow your ego, slow down.

[Tuckerman]

Hang on, if it takes you longer going slow your car is running in the example above, 55mins longer. So that means burning 55mins worth of fuel more, no?

[focus]

Hang on, if it takes you longer going slow your car is running in the example above, 55mins longer. So that means burning 55mins worth of fuel more, no?

If we measured fuel consumption in minutes/gallon, that would make sense.

We don't.

[neck beard]

Hang on, if it takes you longer going slow your car is running in the example above, 55mins longer. So that means burning 55mins worth of fuel more, no?

Correct.... but you use less fuel to travel the same distance even though your engine runs for longer.

[Roo]

What I'd like to know is whether using daytime running lights affects your mpg.

[philippeR]

If we measured fuel consumption in minutes/gallon, that would make sense.

We don't.

You mean
if we measured volumes in minutes, that would make sense.

[tex1230]

Pretty much set the cruise at 65mph

You'll get better mileage if you turn off the cruise control, accellerate on downhill/flat roads only, and just maintain speed on the uphills.

rbtree - Don't turn off the engine while rolling. It's just stupidly dangerous.

[thd]

coast on long downhill grades....it ain't legal to do this out of gear, but I've always done it....hell, even turn off the key sometimes.

Modern cars (post 1990ish) will cut the fuel when coasting, so putting it in neutral is less economical than staying in gear - in gear the downhill keeps the engine running, in neutral gas is used to keep the engine running at idle. For trucks and other primitive vehicles this might not be true though...but owners of those don't care about mileage do they?

[Name Redacted]

Just stay the fuck out of the left lane while you saving all that money$$$$

[f2f]

What I'd like to know is whether using daytime running lights affects your mpg.

daytime running lights waste gas with the extra drag they exert on the alternator.

[uglymoney]

So we lower the speed limit to 55mph. This will create better fuel efficiency in general, and for all those who choose to not obey the speed limit, the police will generate tons of revenue for the state by writing tickets. Simple solution that should be seriously considered. Swallow your ego, slow down.

Terrible thought. I'm waiting for the politicians, insurance companies and policemen to start their 55 mpg propoganda. No doubt it will start soon after the election and with a democratically controlled government we could all be at risk of this kind of punitive legislation. People that want to drive fast should be driving small fuel efficient cars. Higher fuel costs are already going to get this accomplished. Its just a shame we had to wait for a supply/demand crisis to happen rather than a forward looking tax scheme like the Euro's imposed.

I've been driving slower lately at times lately. 27.8 mpg with the Subaru in town on the last tank. That is pretty damned good and that is with the DRL's still connected Shutting it off at lights, staying in high gear, sometimes pissing people off behind me that want to race up to lights and stop signs but normally its just good clean fun. Its fun and it saves, but I can't do it all the time.

[PearlJam09]

I do this on my way to work and sometimes on my way home. I see no point in RUSHING to the office. Set the cruise at like 60-62 and just ease my way into the day. My Outback is averaging 31-32 mpg during the 31 mile commute to work, which is better than the 25 that I get when I drive 75-80. Sure I piss people off by driving slow, but I get in the right lane and ignore them.

And if I have to go anywhere within like 5 miles of my house, I'll usually think about whether or not I can just ride my bike there. 5 miles on the bike takes about 20 minutes, vs the 15 it would take in the car. Not saving that much time, saving some gas, getting some fresh air and exercise. Can't complain.

[Affix Snow]

Drive slow and take the rack off your car!!!!

[DJSapp]

Most Americans drive 15,000 mi/year

15,000/20 mpg * $4/gallon = $3000
15,000/25 mpg * $4/gallon = $2500
15,000/30 mpg * $4/gallon = $2000

Most Americans like to bitch about small things and ignore real issues as well.

[Dromond]

daytime running lights waste gas with the extra drag they exert on the alternator.

However it's probably worth it if they significantly improves safety. Think about how inefficient it is to melt down a wrecked car to make a new one.

...And if I have to go anywhere within like 5 miles of my house, I'll usually think about whether or not I can just ride my bike there. 5 miles on the bike takes about 20 minutes, vs the 15 it would take in the car. Not saving that much time, saving some gas, getting some fresh air and exercise. Can't complain.

Also consider that those shorter trips burn gas less efficiently because the engine is cold for most of the trip. The stop + go driving also puts more wear + tear on the car and gets the worst mileage. I do the same and most of my driving these days is on the highway.

[DougW]

Modern cars (post 1990ish) will cut the fuel when coasting, so putting it in neutral is less economical than staying in gear - in gear the downhill keeps the engine running, in neutral gas is used to keep the engine running at idle. For trucks and other primitive vehicles this might not be true though...but owners of those don't care about mileage do they?

If you have an automatic that is probably true but not if standard. I pop it into neutral on a hill I go faster.

[The AD]

Hang on, if it takes you longer going slow your car is running in the example above, 55mins longer. So that means burning 55mins worth of fuel more, no?

Is this a serious question?

[tex1230]

But does the plane take off?