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MPG at 80


jsharr

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Took a trip to East Texas to visit my parents yesterday.  The 300 suprised me as I was driving faster than normal and still averaged 29.4 mpg and speed was between 75 and 80 most of the time.  Would have been well into the 30's had I driven the speed limit.

Still used to feeding an SUV or truck and getting mileage in the high teens or low 20s.

What sort of miles per gallon do you get on the highway?

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1 minute ago, jsharr said:

Took a trip to East Texas to visit my parents yesterday.  The 300 suprised me as I was driving faster than normal and still averaged 29.4 mpg and speed was between 75 and 80 most of the time.  Would have been well into the 30's had I driven the speed limit.

Still used to feeding an SUV or truck and getting mileage in the high teens or low 20s.

What sort of miles per gallon do you get on the highway?

Yeah, I get about 20 mpg @ 80. It used to be better, but there may or may not be an engine tuner involved.

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Average over 3 years is 24.5 mpg with a 60/40 city/highway split. When tankful represents only highway have been above 30mpg seven times with the two highest 33.13 mpg on 1/25/2018, and 32.69 on 3/20/2018.  Sadly, the highest in 2019 was 29.14mpg.

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17 minutes ago, JerrySTL said:

WoJSTL's 2012 Nissan Altima gets around 33 MPG @ 75 mph. My 2014 Kia Forte 5-door gets a couple mpg better.

Yeah, my 2003 Accord still gets about 33 mpg on highway trips.  It used to get closer to almost 40mpg. I was able to make it to my Mom's old house (500 miles away) with the gas light just coming on so about 13 gallons.  The 2003 Civic still hits high 30s in regular driving.  Probably above 40 on the highway, but that little engine would be working way too hard at 80 to get good economy.  The sweet spot would be in the 60mph area.  We take the Accord anyway on any long distance drives.

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The 300 is so smooth and quiet on the highways that it is easy to forget how fast you are going.  I was overtaking a pickup and as I pulled even, he did the accelarate to keep you from passing move.  Not sure why people do that.  I was on cruise control so I had not changed speed, but he sped up to try and keep me from getting around him.  I gave it some gas and was doing 88 without meaning to.  After I got around him, he slowed back down and I let the car coast back down to 75 on the cruise control.

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I was surprised to get 44 on the way to New York City last year but we were driving on what is called the Merritt Parkway here at speeds of about 60mph.  On the way back I was driving on I 95 at about 80 and the milage dropped of to about 32.  The larger engine in your Chrysler probably has a smaller delta because the extra drag is compensated for easily with but a small change in throttle settings (you have torque)  My 4 cylinder IM requires significantly larger changes in the throttle setting at that speed.  I get the same effect when on cruise control and encounter an up hill section.  The engine RPM goes up for no change in speed (cv transmission)

Different engine/vehicle combinations have different sweet spots.

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3 minutes ago, maddmaxx said:

I was surprised to get 44 on the way to New York City last year but we were driving on what is called the Merritt Parkway here at speeds of about 60mph.  On the way back I was driving on I 95 at about 80 and the milage dropped of to about 32.  The larger engine in your Chrysler probably has a smaller delta because the extra drag is compensated for easily with but a small change in throttle settings (you have torque)  My 4 cylinder IM requires significantly larger changes in the throttle setting at that speed.  I get the same effect when on cruise control and encounter an up hill section.  The engine RPM goes up for no change in speed (cv transmission)

Different engine/vehicle combinations have different sweet spots.

Big v-6 and 8 speed electronic transmission keep the revs way down on the highway but still allow some get up and go when the loud pedal is mashed.

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37 minutes ago, jsharr said:

The 300 is so smooth and quiet on the highways that it is easy to forget how fast you are going.  I was overtaking a pickup and as I pulled even, he did the accelarate to keep you from passing move.  Not sure why people do that.  I was on cruise control so I had not changed speed, but he sped up to try and keep me from getting around him.  I gave it some gas and was doing 88 without meaning to.  After I got around him, he slowed back down and I let the car coast back down to 75 on the cruise control.

I love those azz clown drivers.  When the road is clear, I am a "set it and forget it" type of cruiser, and I easily exposes those types of sheotheads.  Hopefully, there is a special place in hell for drivers like that (probably one level up from the texting and driving section).

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5 hours ago, jsharr said:

Took a trip to East Texas to visit my parents yesterday.  The 300 suprised me as I was driving faster than normal and still averaged 29.4 mpg and speed was between 75 and 80 most of the time.  Would have been well into the 30's had I driven the speed limit.

Still used to feeding an SUV or truck and getting mileage in the high teens or low 20s.

What sort of miles per gallon do you get on the highway?

Great!  My 2013 Honda Fit matches the claimed 31 mpg in local driving, but if I visit relatives that are a couple hundred miles away and avg. 75-80 mph, I get 37 mpg or better.  My tank is only 10.6 gallons, but I can drive from my home south of Baltimore to Wilkes-Barre, PA, and back, just under 200 miles each way, on one tank of gas and that includes a little driving around town.  With no toll roads involved, it's a cheap trip!

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3 hours ago, jsharr said:

The 300 is so smooth and quiet on the highways that it is easy to forget how fast you are going.  I was overtaking a pickup and as I pulled even, he did the accelarate to keep you from passing move.  Not sure why people do that.  I was on cruise control so I had not changed speed, but he sped up to try and keep me from getting around him.  I gave it some gas and was doing 88 without meaning to.  After I got around him, he slowed back down and I let the car coast back down to 75 on the cruise control.

He's the illegitimate brother of the idiot who drives OK but slows to 50 when passing a semi, then speeds back up when they're clear.

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43 minutes ago, RalphWaldoMooseworth said:

The 2013 civic only gets around 30 lately. It used to be more like 35. But that is with a load of four people. The odyssey always gets 20 just like further’s van, but is only 2wd. It used to be more like 25. I notice a decrease of a few mpg in the winter when the gasoline is snot as good. 

The same here.  The car that gets 32 or better in all around driving only gets 28 something in the winter.  You're right, the gas probably contains at least 10% alcohol which should reduce milage about 5%.  In addition for all around driving the engine probably spends too much time in the cold start warmup sequence for the miles driven.......especially around town.

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12 hours ago, maddmaxx said:

The same here.  The car that gets 32 or better in all around driving only gets 28 something in the winter.  You're right, the gas probably contains at least 10% alcohol which should reduce milage about 5%.  In addition for all around driving the engine probably spends too much time in the cold start warmup sequence for the miles driven.......especially around town.

Also remember that the air is a lot more dense. More drag on the car

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3 hours ago, groupw said:

Also remember that the air is a lot more dense. More drag on the car

:rolleyes:

Denser air does indeed cause the engine to need more fuel to maintain the proper ratio.  However that produces more power so you are probably off the loud pedal more.

Air drag differences however.............pretty fn small at street speeds.

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3 minutes ago, 12string said:

I don't buy cars for how much gas they use at 80, it's for how much they can tow at 80 or how much past 80 they go.  If I worried about MPG it would take away all the fun of speeding up when people try to pass me.

I seldom drive faster than 10 above the limit, so 80 is about my max and I was impressed by close to 30 mpg at 80.  Next time I need to make the trip at the speed limit and see if it it worth it to drive slow.

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10 minutes ago, jsharr said:

see if it it worth it to drive slow.

I'll save you some time:  it's not.

It's easy to justify, just do the math:  If you suck up gas at 32 MPG and drive for 3 hours, you use more gas than if you use 30MPG but only for 2-1/2 hours.  So you pollute less.  You're fixing global, warming.  And the less time you spend on the road, the less time you have to hit things, so you're being safer.  And reducing congestion by getting off the road sooner.  Driving faster is just better all around

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13 minutes ago, jsharr said:

I seldom drive faster than 10 above the limit, so 80 is about my max and I was impressed by close to 30 mpg at 80.  Next time I need to make the trip at the speed limit and see if it it worth it to drive slow.

If I keep the motorhome under 70 it will get as much as 10.5 pulling a trailer. When we start pushing more than 70 the fuel mileage drops off fast.  Wo46's car will get upper 30s and it doesn't seem to matter how fast I drive. My F150 pickup 18 to 20 tops but I don't do much more than 5 over.

After looking at this my truck gets better gas mileage then my 500cc single cylinder 2 stroke motorcycle.

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1 hour ago, 12string said:

I'll save you some time:  it's not.

It's easy to justify, just do the math:  If you suck up gas at 32 MPG and drive for 3 hours, you use more gas than if you use 30MPG but only for 2-1/2 hours.  So you pollute less.  You're fixing global, warming.  And the less time you spend on the road, the less time you have to hit things, so you're being safer.  And reducing congestion by getting off the road sooner.  Driving faster is just better all around

Do you really think it reasonable to up your speed by 16+% and only incur a 6% fuel penalty?  It's a possibility but pretty unlikely.  For one thing, the difference in aerodynamic drag on an otomobile is approximately a square function of speed.

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On 12/9/2019 at 2:07 PM, groupw said:

Miata gets low 30s regardless of speed. 75 is 4000 rpm. Redline is 7200. It will happily do that all day. 

I recently did a road trip on 95 up to Philly and back. I paid attention to my rpms at 80, and I was right at 2,600 rpms (redline is high 6k). I think my car spends 95% of its life in the 2,000-3,000 rpm range.

On 12/10/2019 at 6:13 PM, maddmaxx said:

Do you really think it reasonable to up your speed by 16+% and only incur a 6% fuel penalty?  It's a possibility but pretty unlikely.  For one thing, the difference in aerodynamic drag on an otomobile is approximately a square function of speed.

Yeah, there would be a larger penalty in most situations. 

I do think, however, assuming time is a factor and assuming cruising & a true average speed, going 80mph on the highway is a VERY good us of $$$$.  Considering even a short trip of 200 miles will save a person OVER an HOUR at 80 mph vs 55 mph, but only cost an extra gallon or two of gas ($2.50-$5.00), that's a great return on an investment of time.  An 8 hour car trip gets you 640 miles (@ 80) vs 440 miles (@ 55), so it is really in folks best interest to go as fast as conditions warrant rather than pick a fuel efficient speed and stick to it.

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17 minutes ago, Razors Edge said:

I recently did a road trip on 95 up to Philly and back. I paid attention to my rpms at 80, and I was right at 2,600 rpms (redline is high 6k). I think my car spends 95% of its life in the 2,000-3,000 rpm range.

Yeah, there would be a larger penalty in most situations. 

I do think, however, assuming time is a factor and assuming cruising & a true average speed, going 80mph on the highway is a VERY good us of $$$$.  Considering even a short trip of 200 miles will save a person OVER an HOUR at 80 mph vs 55 mph, but only cost an extra gallon or two of gas ($2.50-$5.00), that's a great return on an investment of time.  An 8 hour car trip gets you 640 miles (@ 80) vs 440 miles (@ 55), so it is really in folks best interest to go as fast as conditions warrant rather than pick a fuel efficient speed and stick to it.

That's measuring against a different meter stick.

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10 minutes ago, maddmaxx said:

That's measuring against a different meter stick.

Surely is, but my time (and most folks I know) is worth WAY more than $5 an hour.  So, if I get somewhere an HOUR faster, then I am one happy camper.  If there are folks in the car or folks waiting, the value of going as fast as condition warrant is beyond debatable.

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23 minutes ago, Razors Edge said:

Surely is, but my time (and most folks I know) is worth WAY more than $5 an hour.  So, if I get somewhere an HOUR faster, then I am one happy camper.  If there are folks in the car or folks waiting, the value of going as fast as condition warrant is beyond debatable.

 

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