I would like to have this feature! The "Range" is pretty useless actually. It usually goes to 900 km after a fill and then wobbles all over the place - depending upon speed and topography - until it disappears (replaced by the "VISIT FILLING STATION") just when you need a REAL range figure, i.e.when the tank has under 6 L.
Just a question. Do you think the b200t is a reduced fuel burner?...I compare it with my A190 and the difference is huge (yes, I know this one is 200Hp and turbo.... but still feel my B is quite thirsty....
I filled the car tonight. The OBC said the tank average ("After Reset") was 6.8 L/100 and the pump showed a reality check: 7.36 L/100 km. Average speed was 57 km/h. There was a fair bit of city driving this time.
The 0.56 L/100 km differential is a little higher than usual because I think the fill last time was not as "full" as it could have been. But as I said before, over nearly 8000 km, the difference between OBC and reality is: add 0.4 to 0.45 L/100 km to the car's OBC figure, to get the actual consumption.
And even though the reality check showed a middling 7.36 L/100 km, my overall average is now 7.5 (see the fuel economy icon below in my signature), which would be showing as 7.0 or 7.1 on the "After Reset" screen, had it never been zeroed.
In a few months' time, I expect to have a lifetime actual average of 7.4 L/100 km, so it should be fun getting there!
I did a top up today. The On-Board Computer gave me a 6.7 but I am sure it was about to go to 6.6 (so it was probably 6.655 or so) and the actual fill gave a 6.9. Average speed: 57 km/h.
The source of the distance / fuel consumption variation could be odometer error rather than computer error. The fuel management system knows the volume of fuel injected and the odometer provides the distance travelled.
Maybe you should check the accuracy of the odometer reading by travelling an exact known/ measured distance and comparing the odometer reading. Any GPS system should be able to accurately calculate the distance travelled and if you stop filling up at the first automatic stop from the same pump - then you should eliminate or at least reduce any discrepancy.
Temperature is also a factor as it effects the volume of the fuel as you fill the tank. Errors or inconsistencies in any of these factors will give inaccurate results.
Personally, I would tend to believe the on board computer fuel consumption reading as being the most accurate.
Mike, please let us know if you have or after you test the consumption using a known or GPS calculated distance ( accurate to 2 meters ) - I think you may be pleasantly surprised with the results.
This car says that Three Point Motors in Victoria (went there today) is exactly 89 km away from my house, as says my smart fortwo and my Peugeot 405, and the road sign 800 m from my home. Are all three cars wrong, plus the road sign? Actually the distance to TPM is probably 87 km, but the cars are all showing about 3% over-reads in their odometers. And speedometers for that matter.
I don't have - nor do I want - a GPS, but if someone has a handheld one they'll loan me I would try it.
The computer does not know the exact quantity of fuel injected; it uses an algorithm to estimate the fuel consumption. The engine has a fuel return line to the tank, so if there had been an inline flow meter, it wouldn't mean anything, because a fair bit of fuel gets sent back to the tank.
The OBD fuel consumption formula is not very accurate in certain conditions. For example, on the tank where the car was idled for 5.5 hours, the OBC said the average FE was 7.9, when reality showed it was 8.73. That was 10.5% error, when normally, on my car, measured over 8000+ km, it has 5% error. That particular 10.5% result had everything to do with the OBC's ability to read actual fuel consumption as opposed to speedometer error, because so much fuel was used up when the car wasn't moving at all.
Let's put it this way: if the OBC is right, I am averaging 7.05 L/100 km lifetime now. But I'm not....
Hey Mike,
I was trying to be helpful. Have you tried the decaf?
You don't need to buy or borrow a GPS. Use Google maps or Mapquest to check the distance of your trip to Three Point Motors - road signs are often inaccurate. This would eliminate or confirm one of the variables in your calculations.
Nissan and Honda have both been sued for inaccurate odometer readings, because the warranty expires sooner. So other manufacturers are on notice to have accurate odometers ( I believe the tolerance is +-3%).
From my Prius days, I know many other factors come into play - driving style, tire pressure, temperature, head wind, outside temperature, motor temperature when starting out, weight in the vehicle etc.
When I drove to Abbotsford Airport and back, with a full load, my B200T averaged 7.7 litres, according to the trip computer, and using cruise control at 120 kph, but without really trying to minimize fuel consumption. At the end of the trip, I looked like this
Last edited by CC Ryder : 03-22-2008 at 01:04 PM.
Reason: spelling
Google maps says it is exactly 86 km from my home to TPM. The road sign is not wrong by more than one km, because City Hall in Victoria is about 2 km further away from here than TPM is.
So yeah, at most the speedo/odo error is ~3%, and it's over-reading, as are all my cars.
The fuel calculation is the principal suspect!
So to be totally accurate, my apparent 7.52 L/100 km calculated average should be downgraded to 7.74, after correcting for the odometer error.
Which of course means that the OBC is even less accurate, because it reads 5% less consumption than the calculated data.
I have the same 0.5l/km difference as Mike does, and that after more than 13 fill up (check on my signature). So I guess it's just the OBC that not totally accurate. No big deal, but to keep in mind.
Linear Mode
