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How accurate is the l/100km (mpg) reading?


BrianS

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Just out of curiosity, how accurate have you been finding the displayed fuel economy? L/k or mpg, doesn't matter which, just how accurate a reading have you been getting?

The reason I'm asking is that today I set the cruise at 60kmh (approx. 35mph) I then hit the reset button, and it displayed 6.7L/100km, which converts into about 35mpg US.

I haven't yet had the opportunity to take an extended highway trip to check fill-up to fill-up, so have been monitoring the display. After this reading today, I don't know what to think.

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jkeaton is right...after you are driving and hit the reset and like you said it read 35mpg that is not a real mpg you are getting as it doesn't take into account starting and stopping. only real way of checking your mpg is to use 2-3 tank full of gas and using your miles you have driven and divide to get a true mpg reading also depend on driving conditions and how you drive no one person gets the same but that said about 22-23 on avg for me city and hwy. straight interstate about 24-28 mpg depending on road conditions and how many rest stops..

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I have found mine to be quite accurate (within 0.5 mpg). I only check it on road trips, so maybe that's why. Highway with infrequent stops. In town, mine reads about 19 mpg. On the highway, it reads 25 to 28 mpg. One thing I will say is that our DJs are VERY affected by headwind. The EVIC will read as low as 21 mpg. I have actually gotten as good as 33 mpg (verified) on open roads with lower 65 m/hr speed limits. Too many factors for these mpg readings to be spot on.

Peace.

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I realize that the most accurate method is to do the calculations based on distance traveled against fuel consumed. The MPG meter in my Grand Caravan was "close" but not 100% accurate. It was always out a couple mpg, and always in my favour. When I did the calculations, then I found out the sad truth. :) When I saw the low reading from the DJ, I was shocked... thought, there is NO WAY I am getting that kind of fuel economy, and this thing must be WAY off.

So far, the DJ blows the van out of the water for fuel economy, I still haven't done a hi-way trip to do an actual reading, but just based on what I have to put in the tank for around town driving it's much better.

Hit 500km(approx 300 miles) yesterday, Starting to lose that "new car" smell. :)

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Brian, when you do your first highway cruise you will be blown away. It's a fantastic highway vehicle. We did a 13,000 kilometre road trip through Canada and the U.S. our first year and the Journey performed like a trooper. Comfortable, quiet and good fuel economy and the engine is smooth as silk.

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Brian, I was in Columbus last spring. I keep my little screen on Fuel Economy and reset it every time I fill it up. I was on the loop around the city with the Cruise set for 73, and it was reading either 35.5 or 36.6 mpg. I assume it to be accurate because it measures the flow of gas in relation to the rotation of the wheels.

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I realize that the most accurate method is to do the calculations based on distance traveled against fuel consumed. The MPG meter in my Grand Caravan was "close" but not 100% accurate. It was always out a couple mpg, and always in my favour. When I did the calculations, then I found out the sad truth. :) When I saw the low reading from the DJ, I was shocked... thought, there is NO WAY I am getting that kind of fuel economy, and this thing must be WAY off.

So far, the DJ blows the van out of the water for fuel economy, I still haven't done a hi-way trip to do an actual reading, but just based on what I have to put in the tank for around town driving it's much better.

Hit 500km(approx 300 miles) yesterday, Starting to lose that "new car" smell. :)

Your mileage will improve over time... especially around the 8k mile mark...

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OK, I'm already impressed. Filled up today, and combined city(70%)hi-way(30%) I averaged 12.8l/100km, which is about 18mpgUS. Over 340km/210miles. Not too shabby compared to what I've been used to.

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It is accurate, but realise that it is based on a finite number of miles and fuel used - when initially reset it is an average since reset, but the average is based on an unspecified number of miles, so what you did 2 tanks ago may affect the current reading. Note too that it depends to a minor degree on your tires, for as they wear the circumference of the tires is reduced (by 1-2%) and obviously that impacts on what the vehicle calculates the efficiency as.

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I've noticed that I'm getting a MPG average of about 21/22. That's combined city and highway 32 mile commute to work. The highway I travel is a lot of traffic lights so stop and go the whole way. Really not too bad at all, the Pentastar is a great motor.

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  • 2 weeks later...

OK, finally had the chance to take a short hi-way trip on Thursday. Distance to first fill was 455.3 km(282.9mi) Fuel economy was 9.46l/100km or 29.86/imperial gallon or 24.8/US gallon. Speed ranged from 100km(62mph) up to 130km(80mph). Not too shabby imho, and not broken in yet. Only have about 2300km(1429miles) on it. My Caravan struggled to get 26/imperial gallon.

So far, I'm impressed.

And fuel economy indicator readout was pretty accurate as well.

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  • 1 month later...

I found something interesting on this over the last couple of weeks. We have a 2012 Journey R/T and recently acquired at 2012 Caravan as the second car. It was surprising to find the Caravan had better economy.. way better. which is odd because its the same engine, same age, similar(ish) km's.. but it's a brick on wheels.. and then i noticed something.

when I'm stopped at lights, the caravan reads 0l/100. but the dodge reads something astronomically high.

i put this to the test today, as I was pulling into the driveway I reset the reading, then parked on the driveway for a few minutes. My average fuel reading was climbing at a rate between 10 and 15 l/100 every 5-10 seconds up to about 213l/100 before I stopped.

Given I have a reasonably short commute in traffic I'm not surprised it appears way worse! Anyone else found this?

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Appears at least to have a limit. I tried the same test again when I had a little more time and it looks like it maxed out at 213.8l/100. Pretty impressive! Then not surprisingly my economy figures for the rest of the week have looked pretty bad ending up at 22l/100.

Still need to do a refill to refill test to see what reality is..

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