Best rpm/speed for gas mileage

[Thumper]

Since the gas has go up in my area lately and I just did a 1600 mile trip its got me thinking what is the best speed to go for best gas mileage.

 

I know efficiency will go up higher in rpms and in speed, but at some point load becomes to high. But even if its 150% more efficient at 2000rpms then at 1000rpms you are still squirting fuel 200% more of the time. But then again you are going faster at 2000rpms vs 1000rpms so hmm. Well I found an article explaining alittle bit of it.

 

http://auto.howstuffworks.com/question477.htm

 

So what I gathered is a 280z will be most efficient at about 50mph due to its poor aero, but its light weight. While lets say my new car a Z4 Should be efficient at 60 due to is much better aero, but slightly heavier. Then a Hummer will be best at 40 because of heavy weight, and poor aero drag. So for every mph we go over 50-60mph we are getting worse gas mileage.

 

I'm still not at the point where i'm going to change my driving habits or buy a hybrid but I might go 75-80mph instead of 80-90mph to get my extra 2mpg or more.

[cygnusx1]

But if you go 90mph you get there faster so the engine is not running as long. Does that make your brain hurt?

[Thumper]

But if you go 90mph you get there faster so the engine is not running as long. Does that make your brain hurt?

 

LOL yeah the wear and tear on the engine. You have to consider that in cost oh and your time. Time is money and you spend less time driving more time doing other things. But then you have to factor in.... oh NM

[deja]

My driving theory is to drive fast enough to stay ahead of the wrecks and traffic problems....but not too fast so you catch up with the next wreck or trafiic problem!

My difference in milage to and from DNI:

21.5 mpg on the way down, driving at 75 mph

18.5 mpg going home, I drove a bit faster but had about 15 miles at 25 mph because of a piece of wood in the road, WTF! But that also included the 6 runs I made at DNI.

Considering I got 13 mpg in my old SBC setup, I'm pretty happy with the LT1 and the computer is still learning.

[cygnusx1]

My driving theory is to drive fast enough to stay ahead of the wrecks and traffic problems....but not too fast so you catch up with the next wreck or trafiic problem!

 

That's how I drive too. I like to keep "situations" approaching my windshield rather than my rear bumper. I try to keep my flow slightly faster than the average traffic flow. Enough can't be said about profiling the drivers you are catching up to. Do it. Drive predictively with a plan B.

[rudypoochris]

On my Explorer I go WOT and shift before 1,000rpm around town. Driving a trip that usually takes 2 hours exactly it took me 3:30 due to traffic. I averaged 19.5 using the shift before 1,000rpm tactic in traffic. I am sure 280z fuel injection and torque curve is very different than EEC-IV and Explorer curve. On the freeway and elsewhere I cruise usually 72mph if it is a normal freeway, or 75mph if it is a faster freeway. Mainly because my time isn't worth going 55mph. I think I would see a point or two more in mpg by going 55mph on the freeway. I averaged 21mpg all highway @ 75mph last time I drove it on a 70 mile test. There was a smidge of a tail wind though. I run 36psi all around.

 

In summation you might try going WOT before 1,000rpm or 1,500rpm in a higher numerical gear - if your EFI can handle it. My reasoning behind my madness is that it largely eliminates the restriction of the throttle body. Try it, who knows.

[Brad-ManQ45]

Guys:

 

I have a '96 Town Car, and used to drive up to North Carolina from Atlanta at least twice a week.

 

I got better gas mileage at ~72 MPH than I did at 65.

 

That said, at 65, I was going slower than almost everybody and noone stayed around long.

 

By going with the normal flow of traffic, and keeping one or two cars between me and a semi, I could raise my MPG to 27. (The cars help to elongate that air pocket that is so beneficial in drafting)

 

On my way to DNI , I got 24.3 mpg, and that was running an average of 67 mph.

[MJLamberson]

But if you go 90mph you get there faster so the engine is not running as long. Does that make your brain hurt?

 

When I was about 10 my dad was trying to explain this mpg things and what you said made more sence then what he said, so it did make my brain hurt, lol... All I know is I get very low mpg the way I drive, if there is open road in front of me I am accelerating, but thats just me. Ive said it once, Ill say it again, I dont worry about mpg or the price of gas... its still cheaper and gives more thrills then a ticket to an amusment park:biggrin:

[Gollum]

I really need to get my speedo working so I can at least have a GUESS at my milage.

 

Right now I'm filling up every 4-5 days, and I commute about 20-25 minutes each way. I'm averaging around 75-80mph on the way to work.

 

I drive a ton around town when I'm not at work. My commute is only about 60-80% of my driving every week, if not maybe a little less.

 

If I had to guess I'd say I'm getting around 14-18 mpg. Possibly more but it's hard to say. I also don't think my O2 sensor is working.

 

I still plan on getting this thing tuned well enough to get it to a solid 30mpg car. Might need some aero work to get there though. We'll see.

 

Idealy I'd like to improve the aero and keep the weight down around 2500, and hopefully driving 70 won't be too big of a hit compared to driving 55-60. I don't think I could stand driving that slow on a road trip, or even commute.