Gas Mileage on the Interstate

[ElFenix]

Those specs would not really be related to comparisons of the size of the car for aerodynamic/mileage considerations. They are based on interior volumes.

When talking about large and small for mileage discussions, it's better to simply compare using the actual vehicle dimensions and compare like sizes.

What really sold me on the Elantra (other than the inflated MPG ratings) was how large the cabin felt. I am 6'2"/210lbs and with as much time as I spend in a car, interior space was important. I have much more leg room than I did in any of the other cars I drove (Corolla, Sentra, Focus, Cruze, Jetta and Mazda 3). The car is still really comfy to sit in, it's just been a disappointment in most other areas.

 

[LTC8K6]

"Feels big inside" is subjective, ask any woman.

Park them next to each other. :whiste:

 

[ElFenix]

"Feels big inside" is subjective, ask any woman.

Park them next to each other. :whiste:

OP says "it feels bigger inside"

i post "of course it feels bigger inside, it's the next EPA size class up"

*argument ensues*


oh internets

 

[Ferzerp]

i post "of course it feels bigger inside, it's the next EPA size class up"

It is important to note, the *only* thing the EPA cares about is interior space. They call some very large cars compacts and subcompacts just because they have small interiors.

 

[ElFenix]

It is important to note, the *only* thing the EPA cares about is interior space. They call some very large cars compacts and subcompacts just because they have small interiors.

edit: maybe that's for other people's consumption who aren't aware that the EPA classifies cars by interior space, if so

 

[Ferzerp]

Yes, that was for anyone who doesn't know, because it's a stupid practice really that unless you are aware of it, you'd never think about it.

 

[LTC8K6]

That's why we shouldn't use EPA classes when talking about car size in relation to drag and highway mileage.

We should just compare cars that are about the same external dimensions.

 

[ElFenix]

That's why we shouldn't use EPA classes when talking about car size in relation to drag and highway mileage.

We should just compare cars that are about the same external dimensions.

that's great, i was using EPA classes when when talking about car size in relation to apparent interior room. which was brought up by the OP.


edit: and as caddy says, their cars are pointier than bmw's

 

[deadken]

...
I hope your friend is still happy with his purchase, but I would NEVER recommend a Hyundai to anyone after my shitty experience with this one.

When I asked him about the mileage, he opened his wallet and took out a debit or credit card. Hyundai puts money on it everytime he goes to the dealership and reports the vehicle mileage (total number of miles on the vehicle, not fuel economy). He was covered under the class action lawsuit because when he bought the car it was rated as 40MPG.

He's still happy with the car. He just hates the tires. He got a pretty well equipped model with the larger diameter rims. He keeps on getting bubbles / blisters most everytime he hits a pothole (we live in NY, we have bad roads). He was lucky and the dealership let him get the 'road hazard' coverage after he bought the car (and after he got a bubble in a tire). He says that when the road hazard coverage is up, he will buy a taller sidewall tire. In the meanwhile since they are still replacing the tires for free, he gets agrevated but lives with it. I think he is using the car less during the Winter / Spring months until the potholes are largely filled in.

 

[phucheneh]

edit: maybe that's for other people's consumption who aren't aware that the EPA classifies cars by interior space, if so

It wasn't about me or others knowing/not knowing that they classified in such a way. My comment was that I don't care what the EPA says about it, as it is otherwise usually pretty clear cut what car sits in what segment.

If you call a car a full-size, and you have one or more cars bigger than it in your model line...well, I don't think 'uber-size' is a very recognized classification at the moment.

So what makes sense is, say:

Sub Compact Mid Full
Fiesta Focus Fusion Taurus
Yaris Corolla Camry Avalon
Accent Elantra Sonata Azera
Versa Sentra Altima Maxima

Some like to overcomplicate. Like Germans...go figure, right? I'm just saying that a 'class' should be about a car's competition; not how many square deciliters of children can be stuffed in them.

 

[Fenixgoon]

the short answer is more revs = more gas.

so yes, something like a corvette that's turning 1500rpm at 80mph is going to use a lot less gas than a 4cyl turning 3000rpm.

 

[deadken]

the short answer is more revs = more gas.

so yes, something like a corvette that's turning 1500rpm at 80mph is going to use a lot less gas than a 4cyl turning 3000rpm.

1973 just called and it said that you are wrong
http://en.wikipedia.org/wiki/1973_oil_crisis

Simply put: If what you said is true, the scramble to get away from V8's and get into 6 + I4's wouldn't have coincided with the oil embargos.

What you are saying totally negates displacement. Suppose you have a 6L V8 and a 2L I4, with everything else being equal, you are going to inhale 3 times the air (and therefore 3 times the fuel) with the V8 over the I4.

Of course, everything else would never truly be equal, but I believe that in a similar situation you'll still burn more gas with the larger displacement. All recent cars shoot for 14.7:1 for the air:fuel ratio. So, the computers are striving to burn the same amount of fuel based on how much air is coming in. I think that the biggest factors that aren't going to be equal are going to be engine design, gear ratios (trans + D/U), ECU mapping, and overall efficiencies.

 

[rancherlee]

2010 Fusion 2.5l gets 33-35mpg @ 75mph, sticker says 31 highway. 2012 f150 scab 4x4 5.0l get 19-21mpg @ 75, sticker says 19 highway.

 

[lakedude]

The EPA highway test has a maximum speed of 60mph, and an average speed of 48mph. That is why you are not getting close to the rated mileage at 70mph.

This was true in 2007 and before. Starting in 2008 they introduced new tests including one at faster speeds. See the details tab in the link:

http://www.fueleconomy.gov/feg/fe_test_schedules.shtml

 

[ElFenix]

Some like to overcomplicate. Like Germans...go figure, right? I'm just saying that a 'class' should be about a car's competition; not how many square deciliters of children can be stuffed in them.

and that's perfectly reasonable. my whipping out of the EPA classifications was to illustrate that, yes, the elantra actually is bigger than its typical competitors, in fact, it's considered the next size class up by the .gov.


i would also like to know more about the deciliter of children measurement.

 

[ElMonoDelMar]

I hit a pothole and messed up the front end on my Elantra. I traded it in for a brand new Buick Encore with AWD. I got hosed bad on the trade in value, but I like this car much better.

I'm getting 26/27 mpg combined after 5,000 miles. I'm not sure what "class" this vehicle is, but it seems better all around than the Elantra with only a few mpg less. I can deal with that.

 

[NutBucket]

It's a "classless" car....Buick is trying to create a class with lifted Chevy Sonic. Glad you like it

 

[herm0016]

my volt is getting around 100mpg on a 100 mile trip... running the gas engine gets around 35-40 on the highway at 80 mph.

 

[Crono]

My 2014 Mazda 3 is pretty efficient at highway speed. I get at least 40 mpg when cruising at 70 mph, and often 50+ mpg. My combined fuel economy so far (driven ~5,000 miles so far) is averaging 37.5 mpg.

My 2012 Mustang (V6) would get between 33 and 37 mpg at 70+ mph.

 

[Yuriman]

I hit a pothole and messed up the front end on my Elantra. I traded it in for a brand new Buick Encore with AWD. I got hosed bad on the trade in value, but I like this car much better.

I'm getting 26/27 mpg combined after 5,000 miles. I'm not sure what "class" this vehicle is, but it seems better all around than the Elantra with only a few mpg less. I can deal with that.

Sorry to hear about the Elantra, but at least you like your new car.

A neat chart relating to the thread topic, published by Cummins:

The relative ratios between the "three types" of drag will be different in your car, but a few points can be taken away.

1. Aerodynamic drag increases exponentially with speed. Driving slower will net the biggest returns on the highway, thanks to the laws of physics.

2. Tires are a very significant portion of your total drag, and increase roughly linearly with speed. Low rolling resistance tires really do work.

3. It seems that the various other parasitic losses (drivetrain) are a small portion for large trucks that are geared correctly. In passenger cars, this section will be significantly larger with sportier gearing.

 

[ElMonoDelMar]

It's a "classless" car....Buick is trying to create a class with lifted Chevy Sonic. Glad you like it

It's definitely not a car person's car. It's slow and doesn't handle particularly well. I like the gas mileage and the feel of sitting a little higher than a standard car. The heated leather seats, remote start and AWD should be a nice touch in the winter.

 

[Zorba]

3. It seems that the various other parasitic losses (drivetrain) are a small portion for large trucks that are geared correctly. In passenger cars, this section will be significantly larger with sportier gearing.

It appears the chart ignores losses before the flywheel, such as thermodynamic losses in the engine. For example, for a modern gas engine with a compression ratio of 11.6, the max theoretical efficiency would be 37.5%, so 62.5% of the energy in every gallon of gas goes out the tailpipe or into the radiator.

In realty the actually efficiency is probably quite a bit lower than the theoretical max.

So while aerodynamic losses are large, more than 2/3 of the energy is lost to waste heat no matter what speed you are going.

 

[Zorba]

FYI: My 99 Legacy was rated at 24 (IIRC), but I usually got 29-30 going 75-80 mph. My 06 Legacy is rated at 25, but I usually get 28-39 going 75-80 mph. But my 14 Forester rated for 32 only gets 27 at 75 and 25 at 80 . The Forester is the only car I've ever had that I could notice a difference between 70 and 80.

I think manufacturers are learning to game the EPA tests, so the cars are optimized for rural highway driving instead of real world interstate driving.

 

[soccerballtux]

This year Illinois passed a law increasing the speed limit to 70 MPH on most rural interstates. I am pretty pumped about this considering I drive about 40k miles per year. I know that EPA highway MPG ratings are based on real world driving conditions and aren't optimized for setting the cruse control and taking a nap. Having said that, I am very disappointed with the highway mileage on my 2013 Elantra. In order to get close to the EPA rating of 38 MPG, I have to be driving around 55 MPH. I tend to get around 30 MPG if I push it north of 70 MPH.

My question is this, are there any cars out there that are geared to run efficiently at faster speeds? I understand that air resistance is going to play a major role, but I almost wonder if I would be getting similar gas mileage on the highway in a slightly larger car with a bigger engine. If nothing else, the ride would be much more comfortable and I might not lose that much on my overall gas mileage.

I get best mileage ~55mph too. 34 at 55, 32 at 70-72, 27ish at like 80.
I think something has to do with temperature, or the AC cycling all the time-- terrible milage this last month or so

 

[NutBucket]

FYI: My 99 Legacy was rated at 24 (IIRC), but I usually got 29-30 going 75-80 mph. My 06 Legacy is rated at 25, but I usually get 28-39 going 75-80 mph. But my 14 Forester rated for 32 only gets 27 at 75 and 25 at 80 . The Forester is the only car I've ever had that I could notice a difference between 70 and 80.

I think manufacturers are learning to game the EPA tests, so the cars are optimized for rural highway driving instead of real world interstate driving.

I don't follow your logic. Real world interstate driving in LA means I rarely get above 65

I've been averaging about 30-31 in my Fozzy.