1984 MPG's

[Patman]

Originally Posted By: grampi


Because the only 50 MPG vehicles available today are either ultra-expensive hybrids or electrics. When a reasonably priced high MPG vehicle is available, I'll buy one...


What about the Ford Fiesta? Or the new Hyundai Accent and Elantra? All of these are relatively inexpensive and all of them are capable of real world 50+ MPG on the highway. Forget what the EPA ratings are, people are beating those EPA numbers easily in the real world. (perfect example is my Civic, which is only rated at 34 highway but yet I average better than that for entire tankfuls, my last tank average was 40.2 MPG)

No, you won't get this kind of highway mileage with the AC on, or if you're doing 80 mph, or if you're climbing up lots of hills. But if you're on a flat stretch of highway and set the cruise control to the speed limit, it's entirely possible.

 

[sciphi]

Originally Posted By: Patman
Originally Posted By: grampi


Because the only 50 MPG vehicles available today are either ultra-expensive hybrids or electrics. When a reasonably priced high MPG vehicle is available, I'll buy one...


What about the Ford Fiesta? Or the new Hyundai Accent and Elantra? All of these are relatively inexpensive and all of them are capable of real world 50+ MPG on the highway. Forget what the EPA ratings are, people are beating those EPA numbers easily in the real world. (perfect example is my Civic, which is only rated at 34 highway but yet I average better than that for entire tankfuls, my last tank average was 40.2 MPG)

No, you won't get this kind of highway mileage with the AC on, or if you're doing 80 mph, or if you're climbing up lots of hills. But if you're on a flat stretch of highway and set the cruise control to the speed limit, it's entirely possible.


Exactly. A modern economy-oriented car is more than capable of getting high 40's to low 50's fuel economy on the highway when being reasonable.

 

[milehigh]

Don't forget that back in the early 80's we were limited to 55mph on the highway. In my area now, if you are not running 80mph (75 posted) you'll get run over.

I know that if I keep my highway speed at 55-65 in my Elantra, I can achieve mid-upper 40's without a sweat. As it is now, running 75-85 most of the time, I average high 30's consistently.

 

[Kestas]

Originally Posted By: grampi
I'd buy a 70 MPG vehicle if they were available. It isn't my fault they aren't...

I imagine the vehicle would look Yugo-esque, stripped down, and loaded with expensive engine control devices. If it could pass safety standards, a company could probably make such a car, but they would only sell a handful of them (yourself included). Not worth it for any company to pursue.

You could always try to build one yourself. Start with a Model A chassis, fiberglass body, then add the engine of your choice. Maybe a 3-cyl diesel with a transmission geared to favor economy.

Remember, the absolute name of the game is not mpg, but rather how much it costs in the long run to go from Point A to Point B.

 

[itguy08]

Originally Posted By: Patman

No, you won't get this kind of highway mileage with the AC on, or if you're doing 80 mph, or if you're climbing up lots of hills. But if you're on a flat stretch of highway and set the cruise
control to the speed limit, it's entirely possible.


I thought it's been pretty much debunked that a modern aerodynamic car with a cycling AC will not get better MPG with the windows down. It creates a bunch of drag on the car that the AC does not.

 

[KrisZ]

Originally Posted By: itguy08
Originally Posted By: Patman

No, you won't get this kind of highway mileage with the AC on, or if you're doing 80 mph, or if you're climbing up lots of hills. But if you're on a flat stretch of highway and set the cruise
control to the speed limit, it's entirely possible.


I thought it's been pretty much debunked that a modern aerodynamic car with a cycling AC will not get better MPG with the windows down. It creates a bunch of drag on the car that the AC does not.


I'm pretty sure Patman was talking about driving with AC off and windows up, or slightly cracked open, as we've been having pretty mild temps lately. If you have to drive with windows all the way down, then you're right, it's better to just turn the AC on.

 

[Spazdog]

I wonder if the carmakers will be ready next time gasoline hits $5+ gallon?

Last time, you could go by CarMax with $26,000 and buy a Prius or an Escalade. They were the same price. You couldn't get a new Prius at Toyota, they ran out.

GM seems to have positioned themselves pretty well. The Sonic is a sure thing and the Spark appears to have a very good chance.

Ford took advantage of the commercial sector with the Transit Connect. (they also bolstered the vinyl wrap and decal industry. Seems like every company has a Transit Connect "service truck" wrapped in company logos these days)

Chrysler?

Maybe Fiat is ready to ramp up rebadged Bravos and Pandas at the first hint of $5+ gas.

 

[GMBoy]

Originally Posted By: milehighhyundai
Don't forget that back in the early 80's we were limited to 55mph on the highway.


That is a very large factor in fuel economy and when that is factored into the equation.. a new safer car with a full complement of airbags, sound system, a/c, comfortable ride and more horsepower etc getting 40mpg at 65-75mph speeds is pretty darn good in my book!

 

[OVERKILL]

Originally Posted By: itguy08
Originally Posted By: Patman

No, you won't get this kind of highway mileage with the AC on, or if you're doing 80 mph, or if you're climbing up lots of hills. But if you're on a flat stretch of highway and set the cruise
control to the speed limit, it's entirely possible.


I thought it's been pretty much debunked that a modern aerodynamic car with a cycling AC will not get better MPG with the windows down. It creates a bunch of drag on the car that the AC does not.


I was pretty sure the Mythbusters episode on this pointed to the contrary.

 

[sciphi]

Windows until 60 mph, then A/C thereafter. For maximum MPG's, roll the windows completely up, or just barely crack the back windows to create a draft through the car. It's drag, but not as much as old-school A/C saps from the engine.

60 mph is basically the magic number for aerodynamic drag. Underneath, the car barely uses any power to keep going since the air cooperates. Above, the car is brute-forcing its way through using a ton of engine power.

That reminds me, I need to cycle the A/C on the Cruze. It's been a few weeks since it was last used.

 

[SteveSRT8]

Once again no blanket statement can apply to all cars.

A huge boat reaches its peak efficiency mph much earlier, sometimes as early as 45 mph.

A small econobox may be able to make it to 55 or 60, but even then I really doubt that would be the best mpg. When you do the math it takes a TON more power to go 60 than 45.

Also has a lot to do with gearing. Too many variables to simply declare 60 mph the magic number.

 

[sciphi]

At least for aero drag, 60 is right about the speed at which the power used starts to rise faster than the additional speed gained. It's why slowing down from 70 to 60 has a large effect on wind noise and instant MPG readings.

The cars I've had in the past few years have had 55-60 mph as the number beyond which they start losing lots of MPG's for little additional speed.

 

[SteveSRT8]

Nice. I appreciate you posting what works for you.

But I just can't get behind the idea that any statement regarding aerodynamic drag at a specific speed is applicable to all autos.

Do you think a Dodge Caravan has the same Cd as a Prius? And then we haven't even discussed converter lockup and gearing issues.

Too many variables...

 

[rslifkin]

My Jeep gets it's best mpg around 45 - 50 mph at steady state cruise. It'll hold OD with TC lockup down to 40 or just under, but with the engine lugging along at 1100 rpm, it gets about the same mpg at 40 as 45 - 50, so it buys nothing. Above 50, it starts to drop a bit, and above 60, it pretty much falls off a cliff as far as mpg.

In a more aerodynamic car, depending on gearing, the sweet spot could be pushed up a bit higher, possibly close to 60 or so. Each car is different, so it takes some time to find that car's particular sweet spot.

 

[itguy08]

Originally Posted By: OVERK1LL
I was pretty sure the Mythbusters episode on this pointed to the contrary.


From what I remember (it's been a while since I saw that episode):

1. They used different drivers and no CC. Even holding a constant speed, drivers to make a difference.

2. The AC car ran MAX AC and full fan speed (which is pretty much no cycling). On a highway trip how many run it like that? Most will turn it down so the AC has a chance to cycle. On my car with auto temp control after about 5-10 minutes the fan slows down and the air gets a little warmer as the car cools down.

 

[itguy08]

Originally Posted By: sciphi
That reminds me, I need to cycle the A/C on the Cruze. It's been a few weeks since it was last used.


Don't worry. When you use defrost it's automatically engaged.

 

[OVERKILL]

Originally Posted By: itguy08
Originally Posted By: OVERK1LL
I was pretty sure the Mythbusters episode on this pointed to the contrary.


From what I remember (it's been a while since I saw that episode):

1. They used different drivers and no CC. Even holding a constant speed, drivers to make a difference.

2. The AC car ran MAX AC and full fan speed (which is pretty much no cycling). On a highway trip how many run it like that? Most will turn it down so the AC has a chance to cycle. On my car with auto temp control after about 5-10 minutes the fan slows down and the air gets a little warmer as the car cools down.


The one without the A/C did an additional 30 laps:

 

[sciphi]

Originally Posted By: SteveSRT8
Nice. I appreciate you posting what works for you.

But I just can't get behind the idea that any statement regarding aerodynamic drag at a specific speed is applicable to all autos.

Do you think a Dodge Caravan has the same Cd as a Prius? And then we haven't even discussed converter lockup and gearing issues.

Too many variables...
Originally Posted By: rslifkin
My Jeep gets it's best mpg around 45 - 50 mph at steady state cruise. It'll hold OD with TC lockup down to 40 or just under, but with the engine lugging along at 1100 rpm, it gets about the same mpg at 40 as 45 - 50, so it buys nothing. Above 50, it starts to drop a bit, and above 60, it pretty much falls off a cliff as far as mpg.

In a more aerodynamic car, depending on gearing, the sweet spot could be pushed up a bit higher, possibly close to 60 or so. Each car is different, so it takes some time to find that car's particular sweet spot.


I've only had experience driving cars, not SUV's. Cars are inherently slicker since they're lower to the ground and generally have less frontal area. So their sweet spot may indeed be a bit higher than a SUV.

60 mph being about the limit before MPG's take a nosedive does seem to be pretty constant in both cars and SUV's.

More importantly, it's an easy to remember number for the people who aren't as knowledgeable about cars yet want to improve their fuel mileage.