80mph mpg

[Raduque]

I get 12mpg at 80mph.

 

[CLite]

my civic pretty much matched the EPA mpg at 80mph.
my CR-V mpg is crushed at 80mph, about 20% lower than EPA mpg.

In general sedans are not going to be too badly affected by higher speeds, but any kind of vehicle with a high profile and therefore higher drag is going to have a plummeting mpg.

 

[ThatsABigOne]

26mpg at 80mph

1998 Acura 3.5RL

 

[foghorn67]

My car is the happiest around 75mph. It falls off fast after that.

 

[pandemonium]

80 MPH is like 4200 RPM in my S2000. On the highway, I always wish I had another gear (or three) to shift up into. The gearing is designed so that redline in sixth and drag-limited top speed roughly match up, so it's ideal for racetracks, but not so much for getting to the racetrack. I'm lucky to average 25 MPG with the sticky tires.

That sucks; I didn't realize s2ks were reving that high during commutes.

The only reason I can think of why 6th's gearing is that short is to maintain shifting ratios from the other gears (a sudden drop-off shifting from 5th to 6th with a taller gear would be something drivers aren't accustomed to). If you're pulling or racing, you should never be in your last gear, so honestly it could've been taller while maintaining around the same AFR.

Is yours an AP1 or AP2?

My advice would simply be to go slower on your commutes. I bet you'll get around 30mpg if you were using cruise control at 70mph.

 

[natto fire]

Looks like most of the bases were covered, except rolling resistance. Not sure where you are doing your driving, but after driving real elevations out west then moving back here to the midwest, IMO the only two things to worry about for highway mileage is Cd and rolling resistance of your tires. You have your frictional losses in the atmosphere, tires, and engine parts. Then you have losses accelerating from a stop or up inclines, which can be minimized, especially at cruising highway speeds.

Drag increases at the square of speed, and assuming you are running on properly inflated tires, will dwarf other losses in the grand scheme.

 

[Sidekicknichola]

Cars MPGs are very much a normal bell-curve (obviously skewed a bit because you can't go below 0 mpg).

You'll have a peak (generally around 40-50mph) where you are in your highest gear running a very low RPM. The further you get to either side of this curve the lower your MPGs will go.


My last car was geared a bit higher and 55-57 mph was pretty prime, below 40 or above 72 it dropped really hard/fast.

 

[JulesMaximus]

80mph at about 1600 rpm in my charger, 33-35 mpg. Thank you ZF 8-speed.

Really? Because that car is rated at 18 city/27 highway (with the V6 engine-the V8 engines are significantly worse) and everything I've read about Dodge vehicles is about how bad they are when it comes to fuel economy.

I'd be lucky to ever average over 20mpg on my commute with that car.

 

[nerp]

Really? Because that car is rated at 18 city/27 highway (with the V6 engine-the V8 engines are significantly worse) and everything I've read about Dodge vehicles is about how bad they are when it comes to fuel economy.

I'd be lucky to ever average over 20mpg on my commute with that car.

You're looking at the old 5-speed numbers. I get 34 mpg on the freeway easily. The 8-speed transformed the car.

And everything you've read about Dodge vehicles is out of date if it references anything pre 2011.

 

[foghorn67]

You're looking at the old 5-speed numbers. I get 34 mpg on the freeway easily. The 8-speed transformed the car.

And everything you've read about Dodge vehicles is out of date if it references anything pre 2011.

Pentastar helped too.

 

[LTC8K6]

really? Because that car is rated at 18 city/27 highway (with the v6 engine-the v8 engines are significantly worse) and everything i've read about dodge vehicles is about how bad they are when it comes to fuel economy.

I'd be lucky to ever average over 20mpg on my commute with that car.

3.6l
5a 18/21/27
8a 19/23/31

5.7l
5a 16/19/25

 

[JulesMaximus]

You're looking at the old 5-speed numbers. I get 34 mpg on the freeway easily. The 8-speed transformed the car.

And everything you've read about Dodge vehicles is out of date if it references anything pre 2011.

Edmunds.com seems to disagree with you. This is for a 2013 Charger with the 8 speed automatic.



It's a moot point for me anyway as most of my driving is city with some freeway which could be stop and go and frequently is. I never see highway mileage out of any car around here.

 

[LTC8K6]

Edmunds.com seems to disagree with you. This is for a 2013 Charger with the 8 speed automatic.

The EPA disagrees with Edmunds, and so do I. I just posted the EPA numbers.

 

[JulesMaximus]

The EPA disagrees with Edmunds, and so do I. I just posted the EPA numbers.

It's a moot point for me anyway as most of my driving is city with some freeway which could be stop and go and frequently is. I never see highway mileage out of any car around here so I just completely disregard it when considering a vehicle.

 

[LTC8K6]

It's a moot point for me anyway as most of my driving is city with some freeway which could be stop and go and frequently is. I never see highway mileage out of any car around here so I just completely disregard it when considering a vehicle.

Then stop commenting in a highway mileage thread. :biggrin:

 

[JulesMaximus]

Then stop commenting in a highway mileage thread. :biggrin:

I looked up the mileage and posted a comment. What I said was based on the information I had at the time.

 

[nerp]

I don't give a crap what any Web site or publication says. I know how much gas I put in my car and how many miles I drive. I average about 30 in mixed driving. I push 34 on long highway trips. If I drive like a maniac, it's down to 25.

 

[nerp]

And Edmunds has the 5-speed info incorrectly attached to the 8-speed. But Edmunds isn't necessarily known as a bastion of high quality editing and fact checking. . .

 

[JulesMaximus]

And Edmunds has the 5-speed info incorrectly attached to the 8-speed. But Edmunds isn't necessarily known as a bastion of high quality editing and fact checking. . .

It's a good source for researching a new car. I wouldn't completely discount their information based on this alone. I've found their reviews and invoice vs msrp pricing to be pretty spot on in fact.

 

[nerp]

I've had more coffee. Edmund's isn't crap. I've used it when looking around at the car market. I've just seen some errors here and there. Could just be random that I ran into them of all the reviews on the site.

 

[Howard]

well I can help you a bit with this..
the higher the speed, more air is displaced, and to move through "thicker" air, you will need more energy. The technical term is coefficient of drag. The lower Co drag number the more slippery you are going to be the liquid air.

So what you need is a super efficient body with a big enough engine to efficiently cut through the air without much loss of power.

You could try using blue painters tape to tape up the gaps to make air flow more smooth over the body of the car. However your 80mph drive will eat gas due to the energy required to keep the car moving at 80mph.

very sciencey

 

[SparkyJJO]

The EPA disagrees with Edmunds, and so do I. I just posted the EPA numbers.

And the EPA said I should only get 28, then revised down to 26, when I routinely would get 32. Now I do get 26, but only after upping the power levels a fair amount :twisted: