What does your DTE say when you fill a full tank?
01-30-2010, 08:29 PM
#17
I get around 15.9 or 16 something. Prior fill up said I had 326 and now 275 so I definitely see the difference based on driving style and I do all in town driving with extremely minimal highway (if going 3 exits is even highway mileage). I'm shooting for at least 17.5 or 18mpg city. The 7AT vert is rated for 17.
02-03-2010, 03:46 PM
#19
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I believe DTE is calculated on a much shorter average than the dash does. It recalculated based on the mileage you are getting now(like last 5 minutes or some such), not the average of what you have been getting over the long haul. That is why it changes so much as you drive.
02-05-2010, 01:51 AM
#20
I believe DTE is calculated on a much shorter average than the dash does. It recalculated based on the mileage you are getting now(like last 5 minutes or some such), not the average of what you have been getting over the long haul. That is why it changes so much as you drive.
and that statement isn't 100% accurate either. if you drive on the highway for 15 miles and get 26 mpg you're not going to see 440 mi on your range gauge. you are more likely to see that number never change, than see it increase over the starting DTE.
but yeah, right now i'm curious how people that can't avg over 20 see below 310 after every fill up and those that can avg above 20 see over 340 at time of fill up. i mean this survey may not amount to anything but it's interesting to see car to car variability despite not being 100% sure on driving behavior. I know for person xp that I can't seem to avg above 18.5 and i'm on highways and expressways 70% of the time.
02-05-2010, 08:22 AM
#21
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I don't pay much attention to what it says when I fill up. I do know I can leave my house and have say 160 miles for my DTE, drive 10 miles and have it read 180.
I will try to pay attention to it. I fill up every other day or so, and about half the time I am actually on the highway when I do. I'll try both and see if makes a difference.
I will try to pay attention to it. I fill up every other day or so, and about half the time I am actually on the highway when I do. I'll try both and see if makes a difference.
02-06-2010, 10:25 AM
#24
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This discussion has come up before. The owners manual says DTE is continually updated based on the amount of fuel in the tank and the rate of fuel consumption. The display is then updated every 30 seconds.
There are a few things that we know from direct observation. DTE readout is dramatically affected by driving conditions that can change rapidly: accelerator load, road gradient, and even wind. Also, DTE variance is obviously exacerbated when the the amount of fuel in the tank is lower. So thirty seconds of full on acceleration with 10 gallons of gas in the tank will yield a significantly different DTE than very gentle acceleration with 10 gallons in the tank. Same is true for driving up or down steep hills. In some cases that difference can be quite radical.
Example combining some of these variables: on the way home from Denver last night my fuel gauge (when 12 miles from home) was well below one quarter. DTE was showing 70 miles to go. Conditions - stiff headwind, 28 degress, approximately 1% uphill gradient, 75 mph. Then I went down a 5% grade for five miles, the wind died down completely (other conditions remained constant) and the DTE showed over 100 miles. Assuming 3 gallons in the tank, that is a very significant difference.
The owners manual does not indicate what happens when the car is turned off and the tank filled. But, we know that within 30 seconds of restarting the car after refueling, the DTE should reflect a DTE calculated on the 30 seconds of driving (or idling) immediately after refueling. BUT, if one looks at the DTE immediately upon turning on the car, what one can't know is the elapsed time since the display was last updated. If it was 29 seconds the DTE would reset in 1 second which might yield a different number than what would be seen if the numbers were reversed.
Therefore, I personally believe that the DTE function is pretty much worthless since it (as clearly stated in the owners manual) only reflects 30 seconds of driving. Unless you can observe it on a flat stretch of road, AND calculate the driving conditions for the remainder of your trip before you refill your tank, AND figure in the current number of gallons in your tank - just forget about it.
edit : one additional bit of info. I just filled up my car. Previous DTE was 64 miles. I then turned on the car (on position) without starting the car and it still read 64. I then moved the ignition "switch" to the accessory position (still not starting car). The DTE immediately went blank and then within a few seconds read 411. How the computer determined that new mileage is unknown to me. I suppose it could take use an arbitrary fuel consumption rate or perhaps it could use the fuel consumption rate from the period just before the car was turned off. BTW after a three mile drive home the DTE was 375.
There are a few things that we know from direct observation. DTE readout is dramatically affected by driving conditions that can change rapidly: accelerator load, road gradient, and even wind. Also, DTE variance is obviously exacerbated when the the amount of fuel in the tank is lower. So thirty seconds of full on acceleration with 10 gallons of gas in the tank will yield a significantly different DTE than very gentle acceleration with 10 gallons in the tank. Same is true for driving up or down steep hills. In some cases that difference can be quite radical.
Example combining some of these variables: on the way home from Denver last night my fuel gauge (when 12 miles from home) was well below one quarter. DTE was showing 70 miles to go. Conditions - stiff headwind, 28 degress, approximately 1% uphill gradient, 75 mph. Then I went down a 5% grade for five miles, the wind died down completely (other conditions remained constant) and the DTE showed over 100 miles. Assuming 3 gallons in the tank, that is a very significant difference.
The owners manual does not indicate what happens when the car is turned off and the tank filled. But, we know that within 30 seconds of restarting the car after refueling, the DTE should reflect a DTE calculated on the 30 seconds of driving (or idling) immediately after refueling. BUT, if one looks at the DTE immediately upon turning on the car, what one can't know is the elapsed time since the display was last updated. If it was 29 seconds the DTE would reset in 1 second which might yield a different number than what would be seen if the numbers were reversed.
Therefore, I personally believe that the DTE function is pretty much worthless since it (as clearly stated in the owners manual) only reflects 30 seconds of driving. Unless you can observe it on a flat stretch of road, AND calculate the driving conditions for the remainder of your trip before you refill your tank, AND figure in the current number of gallons in your tank - just forget about it.
edit : one additional bit of info. I just filled up my car. Previous DTE was 64 miles. I then turned on the car (on position) without starting the car and it still read 64. I then moved the ignition "switch" to the accessory position (still not starting car). The DTE immediately went blank and then within a few seconds read 411. How the computer determined that new mileage is unknown to me. I suppose it could take use an arbitrary fuel consumption rate or perhaps it could use the fuel consumption rate from the period just before the car was turned off. BTW after a three mile drive home the DTE was 375.
Last edited by Hi Alt G; 02-06-2010 at 03:32 PM.
02-16-2010, 10:02 AM
#25
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I'm only interested in the DTE at fill up.
and that statement isn't 100% accurate either. if you drive on the highway for 15 miles and get 26 mpg you're not going to see 440 mi on your range gauge. you are more likely to see that number never change, than see it increase over the starting DTE.
but yeah, right now i'm curious how people that can't avg over 20 see below 310 after every fill up and those that can avg above 20 see over 340 at time of fill up. i mean this survey may not amount to anything but it's interesting to see car to car variability despite not being 100% sure on driving behavior. I know for person xp that I can't seem to avg above 18.5 and i'm on highways and expressways 70% of the time.
and that statement isn't 100% accurate either. if you drive on the highway for 15 miles and get 26 mpg you're not going to see 440 mi on your range gauge. you are more likely to see that number never change, than see it increase over the starting DTE.
but yeah, right now i'm curious how people that can't avg over 20 see below 310 after every fill up and those that can avg above 20 see over 340 at time of fill up. i mean this survey may not amount to anything but it's interesting to see car to car variability despite not being 100% sure on driving behavior. I know for person xp that I can't seem to avg above 18.5 and i'm on highways and expressways 70% of the time.
This morning I filled up again. This time I was driving on country roads and in town for most of the time leading up to stopping. I was averaging 19.8 MPG according to the computer and I ended up with 348 for my DTE.
I wonder if the DTE is based on 18 gallons rather than 20. If the car has a two gallon "reserve", that might just make sense. The fuel gauge would show empty at that point too. The numbers would match better too. 407 miles would be 22.6 MPG and 348 would be 19.3.
02-16-2010, 01:04 PM
#26
Normally my DTE after fillup is 320 - 340, with normal city/highway driving at about 18 MPG. I just got back from a trip from Chicago to Minneapolis, 450 miles each way. On the way back after about 650 miles of freeway driving, I filled up and the DTE showed 480!
It was actually pretty accurate, since from that point on in the trip, I covered another 230 miles and the gas guage was on 1/2.
On a side note, gas mileage ranged from 23 on the way up, to 27 on the way back. I think the variation was due to headwinds on the way to Minneapolis. The only other diference was that on the way back I didn't use cruise control and I was going between 50 and 70 because of light snow conditions.
It was actually pretty accurate, since from that point on in the trip, I covered another 230 miles and the gas guage was on 1/2.
On a side note, gas mileage ranged from 23 on the way up, to 27 on the way back. I think the variation was due to headwinds on the way to Minneapolis. The only other diference was that on the way back I didn't use cruise control and I was going between 50 and 70 because of light snow conditions.
02-16-2010, 07:56 PM
#28
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1) get up to 50 MPH on a downhill slop toward the gas station.
2) reset mileage guage.
3) roll into station without using throttle.
4) turn off engine
5) fill up.
I bet it will read 500+ !
02-17-2010, 08:52 AM
#29
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I don't think it will affect it much if at all. It has to keep separate data for the DTE. The only question is how long the time period it uses to calculate MPG. It has to average out over some period of time, otherwise you would see wildly fluctuating numbers as you drive.
02-18-2010, 11:03 AM
#30
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Yeah, when I fill up it's generally around 370 to 380 till empty. That's mainly cause I drive highways all the time. But when I've been driving around city it's closer to 340 or 350.