rets

IMHO, the trip computer's MPG is quite closed to the data I calculated manually by MILES/GALLONS, especially if you do reset the trip computer and odometer each time you fill up the tank. At least in my 04TL the trip computer always seems accurate since I purchased it in Oct.

Depend on your drving conditions, the acutal MPG info is not having much relationship with EPA standards. Most of drivers usually run lower MPG than EPA, but some would get better in some trips. I got the best MPG data in my vibraion zone, at 1500RPM/5th gear/50-55 MPH, about 33 MPG in highway cruising. If, I mean "if", you drive your car in the downhills, you will even find your trip computer displaying the incredible MPG (the trip computer just cannot calcuate your MPG). In this situation, the trip computer will make your total MPG even higher.

paparazzi

Im getting 24 in city and 34 highway at 5280 ft above sea level (Denver) Only have 1200 mi on car.

Kent Hufford

TLGator

Interesting comments, thanks for the additional info!

jzinckgra

As promised, I filled up after work and here's what I got: according to the computer, as I pulled into the station the avg. mpg went from 33 to 32, which probably meant is was really around 32.9 or so. This is why I wish the avg mpg would read out to the 1/10 position. Anyways, I had 321.4 miles on the trip and the car took 10.295, which equates to 31.2 mpg. So basically the computer was reporting about 1.7mpg more than what it should. So, going back to the 37mpg-knock off ~1.7 from that and I end up with aound 35.3mpg, which is still very good. But, I'll definately be repeating the highway trip to double-check. Either way the computer seems to be off by 1-2mpg; certainly not that inaccurate.

rets

jzinckgra, maybe you already posted this and I miss it.

Do you mind telling us again what section of highway you're driving on while getting 37? What octance/brand do you use? What is outside temp if possibe? I suppose it's the sunny day, right?

Perhaps, someone driving that road frequently could provide you some feedback. Thanks.

tlsblack

I believe that the trip computer could register that high in the first 30 miles of driving but I don't think that you actually average that much on a long trip.

I have a 2003 TL-S so I cannot comment on the 2004 first hand. In theory, the two cars should not be too different. The best long term mileage I have gotten was 32.5 on a trip from DC to Boston. I did not use cruise at all and kept it as close to 80mph as possible (Did 470 miles in 6-1/2 hours with a 15 minute stop). I only had my wife and some light bags in the car. In theory, dropping to a consistant 70 would boost my 32.5 to 34 or 35, but I have not seen a lot of posts this high - most likely because not many of us can restrain ourselves. BTW, I am totally stock (Michelin tires) except for a Comptech Icebox.

My wife drives a BMW with a trip computer like the 2004 TL and, although I don't drive it all the time, I have noticed a couple of things. First off, no matter how much I fill the tank (full to first shutoff or if I stuff another 1/2 gallon in with multiple shutoffs), it almost always starts with the same miles to empty. Another weird thing is that if you reset the trip computer when the car is getting good mileage (like rolling down a hill or cruising on a highway), it starts really high and takes a long time to correct itself. If I reset it at the pump while stopped, it seems more accurate.

One other factor is your speedometer calibration which, I understand, varies slightly from car to car. I know for a fact that mine is slightly high (about 1%) on speed and miles. If your Falken tires are a different size, it could impact this more.

Congrats on the great mpg.

pettydw

You'll note the 22% fuel economy discount number on the .gov website for highway is to correct for domestic manufacturers who need to stretch every last 1/10 mpg from their fleets to meet CAFE requirements.

I have always done better the EPA estimates with imported cars, since they tend to gear their cars for real world driving (i.e.: hills, which are not found in Southern Michigan). For example, my '99 Civic Si gets 35mpg on 75mph trips, though it is only rated at 31 mpg highway.

jzinckgra

The highway route is 90 east (from sturbridge, Mass) to 290 east (through worcester) to 495 north, to 95 north right into portsmouth, nh.
I filled up at a mobil station/93 octane. Outside temp was between 74-76 and mostly clear.

rets

1. Trip computer of 04TL could only be evidence for MPG info between 1-50. Any numbers superior than 50 MPG, your MID would present >50.

2. Facts of "miles to empty" is not the direct juxtaposition of "MPG" of the trip computer. In this MPG of trip computer, it's like the total average on the trip (from the last point you reset it to the current moment). But the "miles to empty" uses the shorter trip's MPG to calculate its result. For example, if the MPG shows 17, usually you may get 225 miles to empty after you fill up the tank. But, if you have been cruising on the highway for dozens of miles before entering the gas station and your MPG displays 17, the miles to empty may display 330.

3. Inside Navi's Diagnosis screen, you would see at least 7 items related to this mileage/mpg/gallons info.

They are Sampled FL, Measured RF, Refuel FL, Calculated RF, RAFE, Display Range, and Calculated Range.

4.The result of MPG may be the conjunction of environmental, technical, and personal factors.

Lots of time ppl say they get 21-23 MPG in the city, but I always have 16-19 MPG. This doesn't mean one of us telling a lie. These numbers are just the average data coming out of our cars in the individual situation.

I still think his 37 is kind of possible if counting on the reasonable errors.

My 0.02.

feldmanbd

Has anyone ever figured out why there are 4 fuel measurements in the Navi Diagnostic Trip Computer readout?

I'm pretty certain the first readout, distance, which is in mm, is vehicle speed in millimeters/sec.

The next one, FUP, I'm guessing is milliliters of fuel used per second. 1 milliliter per second = 0.95 gal/hr and the car idles at 0.4 ml/s, which would be about 0.4 gal/hr, which makes sense.

I'm guessing Sampled FL is Sampled Fuel Level, which is what the float in the tank senses and can vary based on angle of the car.

Measured RF is probably Measured Remaining Fuel, which is what you get when you dampen out all the fluctuations in the Sampled FL measurement.

Refuel FL is probably Refuel Fuel Level - my guess is this is the same as one of the above and is used to compare against to determine when the car was filled with gas so the trip computer can reset.

Calculated RF is probably calculated remaining fuel, based on the amount of fuel when the tank was filled and how much the ECM thinks it has put into the engine.

Anyone ever tried dumping in a gallon or two of gasoline to see if that would make calculated RF and measured RF different but not trigger a change in the refuel FL? Maybe this would notify you if someone siphoned gas out of your tank or something.

RAFE - rolling average fuel economy - not sure what the "rolling average" period is for this one but it's certainly less than a tankful.

Calculated Range my guess is Measured RF * RAFE

Anyone figured out the calculation for displayed range? Do they just knock 20 miles off of calculated range or something?

Always something to investigate :-)

Trunk Monkey

iTrader: (1)

Doesn't really seem THAT high...at least not unusual. On my way back to Norman, OK from Denton, TX I average 36mpg. I average 22-24 with all city driving...and that's at an average MPH of around 35. Maybe our cars are freaks of nature?

05TLdcc

wow you guys bumped a 6 year old thread?

Trunk Monkey

iTrader: (1)

Bahaha NOO! You weren't supposed to give in yet I wasn't going to be the one to say it, I was just going to play along

hrod26

That is a stretch of interstate for good mileage...but did you really drive 35 in a 70 mph zone? haha....I made that drive not too long ago and averaged about 85 mph (wasn't looking at the mileage but it was probably 29-31 mpg)

04TLVTEC

It's possible. I usually double check my trip computer with a real calculation that I do myself @ the pump. Over the Summer I drove from upstate NY to Belmar, NJ and got 35 MPG on the way down. The MID is usually close to my real world calculations; it is never off more than 1-2 MPG.

feldmanbd

Actually, my intention was more to discuss the various readouts in the diagnostic trip computer since the last post had already mentioned what they were than to revive a 6-year-old thread. Although I'm easily able to get 33 - 34 mpg driving on I-95 down the east coast - I'm sure if you're driving in the west in the higher elevations where the air is thinner you could easily hit 37.

LaCostaRacer

^feldmanbd - I found your comments very helpful. I think it's much better to reply to an old thread on gas mileage which there have been 100's than to start another one.

I find it interesting how many people claim the MID is not accurate over the years and I have had the complete opposite experience with my MID- it is dead on when you figure that it needs to round to the nearest integer so will be off by +/- .5 mpg anyway.

Also I have no problems getting 30mpg on the highway at 70+ MPH with Pilot Sport AS tires even so 37mpg with more fuel efficient tires in addition to a steady throttle could easily get 37. The real data people almost always leave out in MPG claims is what the average MPH is- the average MPH is a huge predictor for the MPG based on my experience.