31.2 mpg....
Burning Brakes
Joined: Jun 2011
Posts: 990
Likes: 288
When you decline from some MF mountain you can get probably over 80mpg... so the numbers shown on those screens mean nothing until the same picture has fuel tank level, plus what trip a mileage is... when I see those three on the same unedited photo, I'll start believing it is possible ... 
Advanced
Joined: Apr 2012
Posts: 69
Likes: 6
It's not impossible. with an unloaded car and cruise control on most people should be able to get that and more. I just did a 1075 mile loop through southern Colorado - 60% highway 25% mountain passes and 15% city driving approx and got 27.3 avg for the trip. That included one extremely windy day as well. And the trunk was full of catalogs and samples.
set cruise control on that car and drive for 100 miles on the highway. Your totals will be higher than you think possible. I think these cars get great hwy mpgs. I couldn't be happier.
set cruise control on that car and drive for 100 miles on the highway. Your totals will be higher than you think possible. I think these cars get great hwy mpgs. I couldn't be happier.
Banned
Joined: May 2010
Posts: 3,138
Likes: 113
From: Charlotte, NC
I must say i miss the instant fuel monitor from my 08 Honda Accord EX-L w/ navigation. I wish the newer navi interface in the 07-08 TL's could be hacked to get this feature like the 04-06 navigation interface can be.
Cruisin'
Joined: Jun 2011
Posts: 21
Likes: 0
I just had my first chance at a long highway trip and wanted to see how well the RL could do. I drove to Anaheim from San Diego with uninterrupted freeway traffic, average 60 mph, three people and A/C on, no cruise control - and got 32.5 mpg over 86 miles. On the way back with just me and a similar speed, I was at 33 mpg before hitting 6 miles of stop and go traffic and ended the return leg at 31.5 mpg. I pretty much kept to the right hand lane and was definitely trying to optimise the economy but I was very happy to see that these numbers were possible. Driving around San Diego in mixed driving usually gets me approx. 22 - 23 mpg.
Take care.
Take care.
Instructor
Joined: Mar 2012
Posts: 189
Likes: 17
From: Ft. Meade, Maryland
You can get good gas mileage, but it has to be on the highway and with cruise set...so yeah, pretty much once in a blue moon.
Pro
Joined: Feb 2006
Posts: 613
Likes: 15
From: Socal
I can get around 28mpg if I didn't drive over 70 on the highway. If I average 75 on the highway, I usually get around 26.8mpg. I've experimented with cruise control, seems like I get better mileage without having it on because I usually let momentum do its job. Say, there's a down hill stretch, I let the car go to 80ish, and let the momentum take it up the uphill stretch, which I let it go to about 65mph before I really hit the gas again.
Odd thing is, I've been driving hwy for, say 80% of the time with the car, yet my average speed has always read 41mph. Maybe that's what the OP had too?
Odd thing is, I've been driving hwy for, say 80% of the time with the car, yet my average speed has always read 41mph. Maybe that's what the OP had too?
Instructor
Joined: Apr 2010
Posts: 123
Likes: 1
From: UK
I had 500 mls done on one full tank couple years ago. Best mpg on the screen that time was 39 with something. Petrol was Unleaded 95.
This is from few days ago:
This is from few days ago:
Last edited by Pint; Jul 11, 2012 at 01:54 PM.
Cruisin'
Joined: Feb 2012
Posts: 19
Likes: 3
From: LTU
Hey all, this is waht i get usually within 65 mile trip on highway 75-80 MPH & 85% of the trip.
I drive only on LPG.
Had to fine tune the LPG system for like 3 months every few days, but finally i got it right.
In the city i get around14-17 not more. Highway no matter what i never get more than 29mpg on cruize. But its ok with i drive on LPG and its 50% cheapper than petrol. 50liters of LPG can provide me with 270miles until i need to refill my LPG tank, thats on highway & not more that 75-80MPH. The roads here ar not like netherlands have.
I drive only on LPG.
Had to fine tune the LPG system for like 3 months every few days, but finally i got it right.
In the city i get around14-17 not more. Highway no matter what i never get more than 29mpg on cruize. But its ok with i drive on LPG and its 50% cheapper than petrol. 50liters of LPG can provide me with 270miles until i need to refill my LPG tank, thats on highway & not more that 75-80MPH. The roads here ar not like netherlands have.
Cruisin'
Joined: Feb 2012
Posts: 19
Likes: 3
From: LTU
Hey all, this is waht i get usually within 65 mile trip on highway 75-80 MPH & 85% of the trip.
I drive only on LPG.
Had to fine tune the LPG system for like 3 months every few days, but finally i got it right.
In the city i get around14-17 not more. Highway no matter what i never get more than 29mpg on cruize. But its ok with i drive on LPG and its 50% cheapper than petrol. 50liters of LPG can provide me with 270miles until i need to refill my LPG tank, thats on highway & not more that 75-80MPH. The roads here ar not like netherlands have.
I drive only on LPG.
Had to fine tune the LPG system for like 3 months every few days, but finally i got it right.
In the city i get around14-17 not more. Highway no matter what i never get more than 29mpg on cruize. But its ok with i drive on LPG and its 50% cheapper than petrol. 50liters of LPG can provide me with 270miles until i need to refill my LPG tank, thats on highway & not more that 75-80MPH. The roads here ar not like netherlands have.
4th Gear
Joined: Jul 2012
Posts: 4
Likes: 0
Gas Mileage
Most times when I start a new trip and do freeway travel, I have no problems getting high 28 to 30 mpg. I wish I saved the pics I had taken with my car when I finished completing a 507 mile trip. I had 31.9 mpg, car showed it still had 57 miles left to go on the tank. The trip I took with my car involved up and down steep mountain driving, on and off freeway to inner city travel. My average speed for freeway travel is 77 mph. It seems I get better gas mileage at this speed then 75 mph.
Senior Moderator
Joined: Dec 2010
Posts: 31,897
Likes: 7,251
From: Austin, TX
Everyone here does realize that the computer isn't accurate; right? The only way to know your true average MPG for a trip is to divide the number of miles completed by the number of gallons between complete fill-ups.
I have never achieved the computer's estimate by using the real numbers. It is usually more than 1 MPG off.
I have never achieved the computer's estimate by using the real numbers. It is usually more than 1 MPG off.
Instructor
Joined: Mar 2012
Posts: 189
Likes: 17
From: Ft. Meade, Maryland
Everyone here does realize that the computer isn't accurate; right? The only way to know your true average MPG for a trip is to divide the number of miles completed by the number of gallons between complete fill-ups.
I have never achieved the computer's estimate by using the real numbers. It is usually more than 1 MPG off.
I have never achieved the computer's estimate by using the real numbers. It is usually more than 1 MPG off.
Instructor
Joined: May 2012
Posts: 231
Likes: 61
From: Ann Arbor, MI
Everyone here does realize that the computer isn't accurate; right? The only way to know your true average MPG for a trip is to divide the number of miles completed by the number of gallons between complete fill-ups.
I have never achieved the computer's estimate by using the real numbers. It is usually more than 1 MPG off.
I have never achieved the computer's estimate by using the real numbers. It is usually more than 1 MPG off.
How do you know that your method is more accurate than the computer? I imagine there is some variability in exactly how full you fill the tank each time you fill up. My guess is there's probably some degree of error in both methods. Not sure how you'd determine which has the smaller error.
Senior Moderator
Joined: Dec 2010
Posts: 31,897
Likes: 7,251
From: Austin, TX
You are kidding, right? The variability of a full tank is less than a 1/4 of a gallon. Both methods are going off of the odometer to track distance, so any error there will propagate into both calculations. This leaves a significant figure of about 2-3 tenths, 5 tenths at the worst. Even if the variability of a full tank fluctuates that much and the computer was more accurate, then you would see fluctuations on either side of the computer's number. Once again, I have never seen the real numbers come close or surpass the computer's average.How is the computer calculating anyway? Measuring a flow rate, accumulating the amount pumped, and dividing by the distance traveled? What is the error of the flow-meter?
I know my method is more accurate than a computer because I understand basic physics.
Three Wheelin'
Joined: Mar 2005
Posts: 1,966
Likes: 182
You are kidding, right? The variability of a full tank is less than a 1/4 of a gallon. Both methods are going off of the odometer to track distance, so any error there will propagate into both calculations. This leaves a significant figure of about 2-3 tenths, 5 tenths at the worst. Even if the variability of a full tank fluctuates that much and the computer was more accurate, then you would see fluctuations on either side of the computer's number. Once again, I have never seen the real numbers come close or surpass the computer's average.How is the computer calculating anyway? Measuring a flow rate, accumulating the amount pumped, and dividing by the distance traveled? What is the error of the flow-meter?
I know my method is more accurate than a computer because I understand basic physics.
Senior Moderator
Joined: Dec 2010
Posts: 31,897
Likes: 7,251
From: Austin, TX
Owned by the oil companies, or regulated by the Department of Agriculture? Your tin-foil hat is clouding your thinking.I would trust the flow meter at the pump which gets regularly tested and calibrated versus a one-shot design intended for all temperatures. Have you ever filled up a 5 gallon gas can? How far off was the line in the can versus the meter on the pump?
Originally Posted by Wikipedia
The metrology of gasoline
Gasoline is difficult to sell in a fair and consistent manner by volumetric units. It expands and contracts significantly as its temperature changes. A comparison of the coefficient of thermal expansion for gasoline and water indicates that gasoline changes at about 4.5 times the rate of water.
In the United States, the National Institute of Standards and Technology (NIST) specifies the accuracy of the measurements in Handbook 44. Table 3.30 specifies the accuracy at 0.3% meaning that a 10-US-gallon (37.9 L; 8.3 imp gal) purchase could vary between 9.97 US gal (37.7 L; 8.3 imp gal) and 10.03 US gal (38.0 L; 8.4 imp gal) as to the actual amounts at the delivery temperature of the gasoline.
The reference temperature for gasoline volume measurement is either 60°F or 15°C. Ten gallons of gasoline at that temperature expands to about 10.15 US gal (38.4 L; 8.5 imp gal) at 85 °F (29 °C) and contracts to about 9.83 US gal (37.2 L; 8.2 imp gal) at 30 °F (−1 °C). Each of the three volumes represents the same theoretical amount of energy. In one sense, ten gallons of gasoline purchased at 30°F is about 3.2% more potential energy than ten gallons purchased at 85°F. Most gasoline is stored in tanks underneath the filling station. Modern tanks are non-metallic and sealed to stop leaks. Some have double walls or other structures that provide inadvertent thermal insulation while pursuing the main goal of keeping gasoline out of the soil around the tank. The net result is that while the air temperature can easily vary between 30°F and 85°F, the gasoline in the insulated tank changes temperature much more slowly.
Temperature compensation is common at the wholesale transaction level in the United States and most other countries. At the retail consumer level, Canada has converted to automatic temperature compensation and the United States has not. Where automatic temperature compensation is used, it can add up to 0.2% of uncertainty for mechanical-based compensation and 0.1% for electronic compensation, per Handbook 44.
There are many fewer retail outlets for gasoline in the United States today than there were in 1980. Larger outlets sell gasoline rapidly, as much as 30,000 US gal (110,000 L; 25,000 imp gal) in a single day, even in remote places. Most finished product gasoline is delivered in 8 to 16 thousand gallon tank trucks so two deliveries in a 24 hour period is common. The belief is that the gasoline spends so little time in the retail sales system that its temperature at the point of sale does not vary significantly from winter to summer or by region. Canada has lower overall population densities and geographically larger gasoline distribution systems, compared to the United States. Temperature compensation at the retail level improves the fairness under those conditions.
Higher energy prices have raised awareness of this issue for consumers. At the same time, alternative fuel applications are now reaching the retail market and accurate comparisons between them in normal usage are needed. Eventually the basis for retail sales will change from volume units in liters or gallons to energy units such as the BTU, joule, therm, or kWh so that electricity, liquids, liquefied gases and compressed gases can all be sold and taxed uniformly.[original research?]
In some regions, regular required inspections are conducted to insure the accuracy of fuel dispensers. For example, in the US state of Florida, the Florida Department of Agriculture and Consumer Services conducts regular tests of calibration and fuel quality at individual dispensers. The department also conducts random undercover inspections using specially designed vehicles that can check the accuracy of the dispensers. The department issues correction required notices to stations with pumps found to be inaccurate.
Gasoline is difficult to sell in a fair and consistent manner by volumetric units. It expands and contracts significantly as its temperature changes. A comparison of the coefficient of thermal expansion for gasoline and water indicates that gasoline changes at about 4.5 times the rate of water.
In the United States, the National Institute of Standards and Technology (NIST) specifies the accuracy of the measurements in Handbook 44. Table 3.30 specifies the accuracy at 0.3% meaning that a 10-US-gallon (37.9 L; 8.3 imp gal) purchase could vary between 9.97 US gal (37.7 L; 8.3 imp gal) and 10.03 US gal (38.0 L; 8.4 imp gal) as to the actual amounts at the delivery temperature of the gasoline.
The reference temperature for gasoline volume measurement is either 60°F or 15°C. Ten gallons of gasoline at that temperature expands to about 10.15 US gal (38.4 L; 8.5 imp gal) at 85 °F (29 °C) and contracts to about 9.83 US gal (37.2 L; 8.2 imp gal) at 30 °F (−1 °C). Each of the three volumes represents the same theoretical amount of energy. In one sense, ten gallons of gasoline purchased at 30°F is about 3.2% more potential energy than ten gallons purchased at 85°F. Most gasoline is stored in tanks underneath the filling station. Modern tanks are non-metallic and sealed to stop leaks. Some have double walls or other structures that provide inadvertent thermal insulation while pursuing the main goal of keeping gasoline out of the soil around the tank. The net result is that while the air temperature can easily vary between 30°F and 85°F, the gasoline in the insulated tank changes temperature much more slowly.
Temperature compensation is common at the wholesale transaction level in the United States and most other countries. At the retail consumer level, Canada has converted to automatic temperature compensation and the United States has not. Where automatic temperature compensation is used, it can add up to 0.2% of uncertainty for mechanical-based compensation and 0.1% for electronic compensation, per Handbook 44.
There are many fewer retail outlets for gasoline in the United States today than there were in 1980. Larger outlets sell gasoline rapidly, as much as 30,000 US gal (110,000 L; 25,000 imp gal) in a single day, even in remote places. Most finished product gasoline is delivered in 8 to 16 thousand gallon tank trucks so two deliveries in a 24 hour period is common. The belief is that the gasoline spends so little time in the retail sales system that its temperature at the point of sale does not vary significantly from winter to summer or by region. Canada has lower overall population densities and geographically larger gasoline distribution systems, compared to the United States. Temperature compensation at the retail level improves the fairness under those conditions.
Higher energy prices have raised awareness of this issue for consumers. At the same time, alternative fuel applications are now reaching the retail market and accurate comparisons between them in normal usage are needed. Eventually the basis for retail sales will change from volume units in liters or gallons to energy units such as the BTU, joule, therm, or kWh so that electricity, liquids, liquefied gases and compressed gases can all be sold and taxed uniformly.[original research?]
In some regions, regular required inspections are conducted to insure the accuracy of fuel dispensers. For example, in the US state of Florida, the Florida Department of Agriculture and Consumer Services conducts regular tests of calibration and fuel quality at individual dispensers. The department also conducts random undercover inspections using specially designed vehicles that can check the accuracy of the dispensers. The department issues correction required notices to stations with pumps found to be inaccurate.
Instructor
Joined: May 2012
Posts: 231
Likes: 61
From: Ann Arbor, MI
That said, I do trust the pumps to be accurate in terms of how much gas they shove in your tank versus how much they charge you. What I don't know (and have no way to determine) is the consistency of a full tank. As that same article mentioned, gasoline will expand and contract significantly with temperature. If you fill your tank on a cold day, how much extra gas will your tank hold than if you filled up on a 100 degree day? Pumps shut off when a certain pressure is reached at the nozzle. Is this constant pump-to-pump? Will pumps shut off more quickly if the flow rate is higher? These are all things that could change how much gas goes in each time.
I haven't done the manual vs. computer comparison myself, so I don't know what kinds of differences we're talking about here. I was just challenging the assumption that the manual method was more accurate. The most compelling fact I've heard so far that the manual method is more accurate is that it gives consistently lower MPGs.
Senior Moderator
Joined: Dec 2010
Posts: 31,897
Likes: 7,251
From: Austin, TX
You forgot to use your red text on your first sentence.
I generally use the same station (between 2 nozzles on the same pump) every two weeks. Thus, the variation in temperature is minimal, and the variation in pump is eliminated. Even with the expansion factor, we are only talking 0.15 gal/25 degrees F. When I do my manual calculation, I will round to the nearest 0.25 or 0.5 to compensate for such errors.
I generally use the same station (between 2 nozzles on the same pump) every two weeks. Thus, the variation in temperature is minimal, and the variation in pump is eliminated. Even with the expansion factor, we are only talking 0.15 gal/25 degrees F. When I do my manual calculation, I will round to the nearest 0.25 or 0.5 to compensate for such errors.
Senior Moderator
Joined: Dec 2010
Posts: 31,897
Likes: 7,251
From: Austin, TX
Red text = sarcasm. While I realize that I made a silly error in my post, dismissing the validity of my statement on such a basis would be rather harsh IMHO.
Given the amount of crap I give people for typos and language errors, I probably deserve it though.
Given the amount of crap I give people for typos and language errors, I probably deserve it though.
I didn't remember typing that, but since it was in a quote with my name on it, I figured I should own it. 
Drifting
Joined: Apr 2001
Posts: 2,391
Likes: 45
From: MA
This past weekend I got 28.8 MPG on a 1:10:00 trip. I was going between 70MPH and 80MPH. I noticed that my RL gets better gas mileage in the HOT weather, weird. However, I am still averaging around 19MPG overall.