Most efficient speed?
- Thread starter Lederman
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1engineer
Moderator
Passenger vehicles of all types will "hit" their advertised mpg numbers at around 55 mph. Slower than that (say 45-50 mph) will net you an increase. Higher than that (60-80 mph) will net you a decrease. Changing the body shape (front bumper, roof rack, cargo box, taller tires, etc), adding weight or adding wider tires will also cause a decrease in efficiency. It will look cool but it will cost you accordingly. Here are a few graphs for the lesson of the day:
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Good question. It would help if you mentioned whether you were driving around town or on the highway, but I'll attempt to help. In most cases driving slower will always result in the best gas mileage. For example on the highway, driving 55, if possible, will result in close to the best mileage a stock 4Runner will get.
There are quite a few things that make the vehicle less likely to achieve great mileage starting with the drag coefficient. For the 13, it's 0.36. Using a curb weight of around 4500 pounds, not taking into account any wind speed or direction, that itself, is a hurdle to contend with. I'm hoping you didn't buy your truck to get great gas mileage because it simply isn't too capable.
Another thing to keep in mind is that as you increase the speed, the air resistance is greater and that has to be overcome. The result is, burning more gas, to put it simply. Obviously, the more aerodynamic the vehicle, the higher the threshold will be as far as wind resistance.
Personally, I would recommend 55 on highway to get the best mileage...all that is considering your truck is stock, tires are inflated to the correct pressure and you aren't carrying anything more than what you need.
There are quite a few things that make the vehicle less likely to achieve great mileage starting with the drag coefficient. For the 13, it's 0.36. Using a curb weight of around 4500 pounds, not taking into account any wind speed or direction, that itself, is a hurdle to contend with. I'm hoping you didn't buy your truck to get great gas mileage because it simply isn't too capable.
Another thing to keep in mind is that as you increase the speed, the air resistance is greater and that has to be overcome. The result is, burning more gas, to put it simply. Obviously, the more aerodynamic the vehicle, the higher the threshold will be as far as wind resistance.
Personally, I would recommend 55 on highway to get the best mileage...all that is considering your truck is stock, tires are inflated to the correct pressure and you aren't carrying anything more than what you need.
Thank you for the responses.
In my growing fleet of vehicles I have a Prius, a Volt and now finally a bigger car , the 4Runner (my second the first being a 2003). My wife drives a Fiat 500 and loves it, go figure.
The two hybrid cars operate more efficiently at slower speeds. The 4Runner EPA estimates indicates less efficiency at slower (city) speeds.
I have driven hybrids since 2005 and use the cruise control in town as well as the highway. I typically set the cruise at 35 for all city driving other than residential then it is 25. Because the EPA estimates for the 4Runner indicate more efficiency closer to 55 I'm hoping to see some data that would indicate the 4Runner to be most efficient at 45 mph.
On the highway I set the cruise at 75, so the MPG kinda goes out the window for all three vehicles.
I understand the difference is marginal.
Thanks for the discussion I appreciate it.
In my growing fleet of vehicles I have a Prius, a Volt and now finally a bigger car , the 4Runner (my second the first being a 2003). My wife drives a Fiat 500 and loves it, go figure.
The two hybrid cars operate more efficiently at slower speeds. The 4Runner EPA estimates indicates less efficiency at slower (city) speeds.
I have driven hybrids since 2005 and use the cruise control in town as well as the highway. I typically set the cruise at 35 for all city driving other than residential then it is 25. Because the EPA estimates for the 4Runner indicate more efficiency closer to 55 I'm hoping to see some data that would indicate the 4Runner to be most efficient at 45 mph.
On the highway I set the cruise at 75, so the MPG kinda goes out the window for all three vehicles.
I understand the difference is marginal.
Thanks for the discussion I appreciate it.
cbreze
Member
Wondering if anyone else uses their cruise control in city driving. It seems it would be a constant on/off situation and annoying. The few times I tried, it was like that. I also found myself trying to keep it on as much as possible which led to distractions and possible unsafe conditions. Anyone care to comment on cruise control for "in town" city driving?
Only the people that want to get honked at and flipped off, but it's a trade off ya know.
If I'm driving on a business trip, there's some decent scenery and little traffic, I'll leave early and set cruise to 55 just for fun. Sometimes I'll catch up on a good book or doze off a little. End the end...55 is not practical in most situations, but it's probably the best for MPG.
At 75 mph the Prius gets about 41 mpg and at 80 mph it's down to 36-38.
The Volt, once the battery is depleted, gets about 34 mpg at 80 mph.
I see your point regarding the hybrid vs 4Runner mileage!
When I drove to Florida with 3 kids, a roof box, and two bikes on top of the Prius I saw 25 mpg. The engine was screaming for the entire 1400 miles.
I'm going to try 40 mph in town and 55 on the short highway sections while commuting.This should put me slightly slower than traffic and off the brakes. I'm hoping to see 19 mpg in around town commuting situations.
On the highway I'm going with 75 mph.
Thanks again for the thoughtful discussion.
The Volt, once the battery is depleted, gets about 34 mpg at 80 mph.
I see your point regarding the hybrid vs 4Runner mileage!
When I drove to Florida with 3 kids, a roof box, and two bikes on top of the Prius I saw 25 mpg. The engine was screaming for the entire 1400 miles.
I'm going to try 40 mph in town and 55 on the short highway sections while commuting.This should put me slightly slower than traffic and off the brakes. I'm hoping to see 19 mpg in around town commuting situations.
On the highway I'm going with 75 mph.
Thanks again for the thoughtful discussion.
There aren't any freeways around here. Even the interstate is 55 in town.
Years of trying for the best mileage has acclimated me to a less frenetic pace.
Thanks again!
philsey
New member
[MENTION=98371]Lederman[/MENTION] Finally, another local. I'm in R.I.
My mileage experiences (using the OBC):
17-19 around town, driving like a Grandpa. (I'm now the guy I used to flip off). I also use S4 in town below 40 mph to prevent that 5-4-5 hunting.
25 mpg at 55.
22 mpg at ~70.
From what I've read, my 4R seems to get a bit better mileage than many I've read about.
My mileage experiences (using the OBC):
17-19 around town, driving like a Grandpa. (I'm now the guy I used to flip off). I also use S4 in town below 40 mph to prevent that 5-4-5 hunting.
25 mpg at 55.
22 mpg at ~70.
From what I've read, my 4R seems to get a bit better mileage than many I've read about.
eddiebx
New member
I think the accuracy all depends on how close your driving pattern happens to match the computer's current formula, lol. Sometimes I'm dead on and other times I'm about 1-2 mpg off from the computer's calculation vs manually calculating. If you are into knowing the utmost accuracy, definitely do a manual calculation to keep track.
Victor_inox
New member
that sounds about right.
1000MPH
Senior Member
Love that comment about using CC in town. Does not compute for most of us I imagine.
I like to get good mileage but I'm not driving slower than the posted limit to achieve this. EVER!
My numbers are slightly better than [MENTION=51186]philsey[/MENTION] 's
25 @65-70 (65 limit hwys) and 22 @ 70-80 (70 limit hwys)
I heard those tiny little Fiats only get about 30mph.
I like to get good mileage but I'm not driving slower than the posted limit to achieve this. EVER!
My numbers are slightly better than [MENTION=51186]philsey[/MENTION] 's
25 @65-70 (65 limit hwys) and 22 @ 70-80 (70 limit hwys)
I heard those tiny little Fiats only get about 30mph.
1engineer
Moderator
http://www.toyota-4runner.org/5th-gen-t4rs/146548-estimated-remaining-gas-milage.html I explained how I think it works in post #5 in that thread. There are hundreds of threads out there on this topic.
4Run4YourLife
New member
I get very similar number with my 4Runner. I always assumed the people getting bad mpg's have a bunch of mods and the extra weight is a killer.
LandCruiser
New member
All things being equal, your drag is going up exponentially according to v^2, so the faster you go, the increasingly worse your Toyota-shaped brick will do fuel economy wise.