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Apr 28, 2017 11:52:25 GMT
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I'm looking at doing a mini-tat-tour as there are a couple of folk wanting stuff delivered and it's a good excuse for a few days away from the madhouse I call home  Receipts are here for a few tours in the past so I decided to work out my MPG figures, then I know what it will cost me in petrol to deliver the stuff. To me this sounds like a sensible thing to do, no obvious silly mistakes so far. Right?  Assuming : Petrol is sold in liters, convert by 4.55 (ish) to get gallons, right? Mileage covered / gallons = MPG. Simple, yes? So what went wrong  According to the simple formula above, I'm getting somewhere between 15mpg and 85mpg. I'd like to think the mid-point 50mpg is true, but I have doubts. Assume nothing, I know I've gone wrong but have the receipts - and wrote the mileage on each one when I filled up. Can anyone spot the obvious mistake that I've missed???  Pic as per the rules...  |
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Apr 28, 2017 12:26:20 GMT
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So with RRG 15, I worked it out as 18.26 Gallons to cover 820 miles? Which comes back at 44.9mpg?
RRG16 24.24 Gal to 848 = 34.98mpg
If you start with a full tank & brim it each fill up that should help keep the mpg calcs consistent.
If you start with half a tank and finish with a full tank, the calcs arent going to make any sense
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Last Edit: Apr 28, 2017 12:29:41 GMT by joem83
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luckyseven
Posted a lot
Owning sneering dismissive pedantry since 1970
Posts: 3,839
Club RR Member Number: 45
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Apr 28, 2017 12:29:26 GMT
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You get sixteen miles to the gallon!? /jealous  |
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Last Edit: Apr 28, 2017 12:29:41 GMT by luckyseven
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Wilk
Part of things
Posts: 528 
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Apr 28, 2017 13:25:15 GMT
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I use milagekeeper app
Start with full tank and fill to top each refill. V easy to use and free
Average around town is 19 & best on a run is 31 (woo hoo)
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If it can be fixed with a hammer, then it must be an electrical fault
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Apr 28, 2017 14:03:38 GMT
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Should have said - I always fill to the brim before I start so zero miles on the calculation is with a full tank. When I refill I always fill to the top (when the pump cuts out - this *should* be full), then a bit more to make sure... joem83 correct - November '16 is 297 miles / 12.27 gallon = 24mpg The bit that confuses me is the massive difference on different trips (15mpg might be overloaded with lots of roadworks, but 85mpg  ) The 25mpg-35mpg figures don't surprise me so my figures aren't all daft...  |
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rude
Part of things
Posts: 537
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Apr 28, 2017 15:24:45 GMT
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I'm currently pursing a mpg effort. Max I'm getting on a daily run is 31.4 mpg and I have to try hard to get that and keep the rpm to 1700ish. It's averaging at about 27mpg though with some town driving and traffic lights. I actually dislike accelerating at the moment and use lorries to keep my speed in check.
I'm swapping the pipercross filter next week back to standard to see if I can squeeze more mpg out of it and the fact that these filters actually hamper performance on the 6 series... or so I've read.
It's becoming a bit of an obsession really and I am having inpure thoughts of buying a cheapo Citroen C2 and stripping the weight out of it for ghits and siggles. Help me.
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1986 Haunted BMW E24 635CSi
1999 Povo spec BMW E36 1.8i Touring Work Hack
2001 Petrol annihilating Discovery V8
2000 Jaguar S Type 3.0 V6 ~NEW~
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Apr 28, 2017 17:25:04 GMT
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rude - is that a BMW 6 series? I had an E36 328i with onboard computer a while ago, once managed 35mpg but it was a painfully slow journey (55mph tops, no accelerating, no braking, etc..) Also ran a few 1.5D 106s, tried measuring them but a tankful lasted so long I kept forgetting to check - think it worked out about 70mpg on one trip  Have fun with your project
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rude
Part of things
Posts: 537
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Apr 28, 2017 20:03:47 GMT
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Yes, 1986. I used to try and get it up to 36mpg, once was nearly 38 but it's not set up right at the moment. 65mph seems about the sweet spot but it's not shifting past 31.4mpg.
Gawd knows what the discovery is, that's why they don't have a fuel computer fitted, to stop drivers having a heart attack and the missis thinks is it's got a fuel leak! I reckon it sinks to single figures around town!
My old mates escort turbo was the most shocking I've ever seen, switch high boost, boot it and the fuel gauge dropped like a Speedo!!
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1986 Haunted BMW E24 635CSi
1999 Povo spec BMW E36 1.8i Touring Work Hack
2001 Petrol annihilating Discovery V8
2000 Jaguar S Type 3.0 V6 ~NEW~
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Apr 28, 2017 20:13:30 GMT
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Rr15 and rr16.
Almost the same milage, half as much fuel.
my guess you filled up twice on the first trip (on the way and on the way back) and only filled up the once, when you Left home on the next year.
My guess is you lost one of the reciets for rr2015.
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ChasR
RR Helper
motivation
Posts: 10,241
Club RR Member Number: 170
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Apr 28, 2017 20:36:59 GMT
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You didn't put in a reference mileage for the start. I.e, Brim it and then work out your MPG from the next fill
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Apr 28, 2017 21:46:27 GMT
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^ ChasR - I should have explained, all milages are from the trip meter. All tours started with a a brimmed fuel tank and zero'd trip miles, to make the MPG calculations easy. Info updated as you suggested (see the grey columns), column "stage" is mileage between fillups, this with gallons gives the MPG. The column on the right is the bit I can't believe, it shows MPG for each tankful and varies massively (even ignoring the "special" 84mpg figure) Calculation is column "stage" / "gallons" = "mpg"  The suggestions are all appreciated, I know I've done something daft I just can't see what it is |
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Ryannn
Posted a lot
Posts: 2,421
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Apr 29, 2017 15:38:02 GMT
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I just use the fuelly app. Works it out for you and tracks it!
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Apr 29, 2017 16:29:21 GMT
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The obvious mistake? You forgot the return trip was on the back of a recovery truck....😂😂😂
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I just use:
MPG = MILES SINCE LAST FILL-UP / (LITRES PUT IN THIS FILL-UP x 0.219969157)
Obviously brimming the tank and resetting the trip meter every time.
This tells me that despite my TDCI fuel computer telling me I'm averaging 70-odd MPG, I'm actually getting more like 45!!
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)
