When I fill up my tank, my mileage range says I can go about 200 miles before empty. This is filling up at gas station and then checking range. Is this normal. My 2000 C5 A4 would read somewher around 400+ after a comlete refill. Is this normal? Is one of my tanks not registerring? I have 470 miles on it currently.

 

What's your avg mpg*18? I typically show around 350-360 on a full tank.

 

Did you reset all of the numbers after you filled up?

 

Mine read way low (100 Miles) the first one or two tanks after I got it...but eventually it got to where it reads just shy of 400 when I fill it up.

 

Yep, I usually see 360-380.

 

The car calculates miles to empty by multiplying a moving average fuel economy number by the amount of gasoline in the tank. Only sensible way to do it really.

The car figures out how much gas remains by subtracting the amount of gas used (it knows this precisely since it meters it out with the fuel injectors) since the last fill up from the capacity of the tank.

The running average fuel economy is displayed in the DIC. If the average MPG reported by the DIC is low, your calculated range will be low. If the average is high, so will be the range. Since my average fuel economy shows better than 23 MPG, my range figure is slightly in excess of 400 miles after a fillup.

 

Yes i reset estimator. But when I turn car off and fill up, then turn car back on and check it say 200 before empty for the total mileage of the tank. Granted at this point I havent even moved the car just started and checked. Being a former c5'ver yhis is the first thing I check because I want to see how many miles the car is going to give me. After I pull off and if i driver 55 or 85 thats another thing. I am looking for good beginning balance that is why I am wonderring if one of the 2 tanks is not registerring. 200 miles to the fill up just seems like it is only reading 1 tank. I dont want to keep filling up because it says I have 50 iles till empty persay you know what I mean. Like driving a car with a malfunctioning gas hand.

 

I am on second tank. The first tank was when i purchased last Sunday. Tank was full because the dealer gave me a voucher for 93 octane and told me to go and filler up. It was almost empty, about 50 bucks to filler up. 200 miles til empty registered before i hit the road after fill up. Drove about 55-60 miles for that tank. getting use to difference in c5 - c6, didnt want to hi-ho-silver the extra horses plus it rained that day and the next. Filled her up last night and again 200 miles before empty was the register upon checking before moving. Car is not a daily drive is why I only refilled yesterday. I have an apointment for onstar upgrade next monday and I just want to make sure I dont have something else they should be looking at.

 

It should adjust to the type of driving you're doing within the first couple of tankfulls. I would expect mostly city driving to result in at least a 250 mile range and mostly highway to be close to 400...unless you're on it alot.

 

killa 380-
What is the mpg read out on your car? It must be showing in the 13 mpg range. If not you might want to have a dealer check it out.

 

thats strange, my c5 use to calculate based on that tank full and I was getting 400+ estimated from filling tank. It would then start to deduct from that tank full number based on driving habits. I was registerrung from fill tank then checking before I moved the car out of gas station. trhis was 400+ and all I did was drive around town on saturday and alittle on sunday. The way c5 read was 400+ miles to the tank, I dorve it to north carolina once stopping at the station because I was following cousin in a durango (truck was drinking). I came back by myself so I ran 100 mph at 1am on 95 straight for about 200 miles (75mph speed limit) until I reached Virginia then about 70mph to maryland then 55-60. MPG was about 34-36 mpg at the higher speeds and I made it home on a half of tank. I got home and checked the DIC to see how much further I could have gone. I could have gone to New Jersey about 150+miles. I gained MPG by driving faster in the C5. But the DIC registers the Tank of gas, octane of gas. The computer is suppose ti set varible timing based on octane and give you a guesstimate of total mileage before you move the car. Driving habits and actual mpg city / hwy comes into play after to start to drive that is my the DIC has a fuel setting that is always recalculating and one that adjust as you progress showing you average mpg. 350+ full tank fill up sounds like how it is suppose to start out and if one ends up with 100 mpg that is where driving habits start to ddeduct from fill up status IMO.

 

You have some interesting ideas, but I can't see where octane, timing, or any other variable is required or would be useful to calculate "RANGE", except for two basic pieces of information:
a) an estimate of historical miles per gallon,
b) quantity of fuel currently in tank.

According to the C6 manual:

Fuel Range: The range calculates the remaining
distance you can drive without refueling. It is based on
fuel economy and the fuel remaining in the tank.

The fuel economy data used to determine fuel range
is an average of recent driving conditions. As your
driving conditions change, this data is gradually
updated automatically.

 

That's my understanding too. I also don't thinkit keeps track of how much fuel has been consumed to determine how much is left in tha tank. That wouldn't work if person didn't fill their tank completely.

 

Fuel Range: The range calculates the remaining
distance you can drive without refueling.

- Exactly, the range before refueling. When filling up to full that is calculated the range before refueling starts there (full and ready to start calculating MPG per gallon (It is based on fuel economy and the fuel remaining in the tank.(Full tank starting)) This would be the initial point before refueling AGAIN, full tank.

The fuel economy data used to determine fuel range
is an average of recent driving conditions. As your
driving conditions change, this data is gradually
updated automatically.
This is where the driving habits come into play and is either dead on or short of prediction, This is where the MPG and estimated MPG si calculating constantly because I am now expending fuel for example if I drive like im on the track as a habit

 

I took a drive today and my range showed about 410 after I filled up.

 

About 375

 

I definitely need to drive more aggressively! :bb

 

Mine normally reads about 330 after a fillup and that is right in line with what my average mileage has been. If I'm on a trip though it will climb up as I'm getting 28+ for the most part.