Fuelly analysis: MPG by Recorded Fuelings

[rfernatt]

I was playing around with Excel 2007 and wanted to see how MPG varied over the number of refuelings at Fuelly. Intuitively, one would expect that more active Fuelly users are probably more fuel conscious and this seems to bear that out. Plus, the more refuelings you have, the more likely that the vehicle is broken in and achieving its best mileage. I'm using 2008 and later vehicles.

I'm not really trying to make any point, just a "what if" curiosity kind of thing on a slow Friday afternoon - might as well get more familiar with that blasted Microsoft 'ribbon'.

[jwight]

Will be interesting to see what the 2010 Prius mileage is after that many fill ups.

[Bill Marshall]

I have a prius & a fortwo. My experience is just the opposite of those 2 graphs.

[rfernatt]

Originally Posted by Bill Marshall

I have a prius & a fortwo. My experience is just the opposite of those 2 graphs.

Could be. The graph is averaging the experience of dozens of Fuelly users that have filled up at least 10, 20, 30, etc. times. Individual experience could be vastly different.

The Prius average is likely dropping somewhat at the end due to fewer and fewer vehicles being counted in the average. As the number of cars being counted in the average drops, the more susceptible the data becomes to variation caused by a couple of outliers. For instance, at 50 + fill-ups, there are only 26 smart owners being counted and 10 Prius owners. So, there are relatively few owners with a large number of refuelings posted on Fuelly and I'm sure that's skewing things for all vehicles.

It's just an Excel exercise confirming the idea that avid Fuelly users are likely to be more fuel conscious regardless of vehicle make. Not too much of a stretch, I know, but it's interesting to look anyway.

[tvengineer]

Anyone with 100 fillups on a smart must also be doing a lot more highway driving, hence the higher MPG..

I only fill up my smart every 3 weeks ... do almost NO highway driving and my MPG is in the mid to low 30s'... it will take me almost SIX YEARS to get to 100 fill ups!!! (at my present rate of consumption :-) )

[rfernatt]

Originally Posted by tvengineer

Anyone with 100 fillups on a smart must also be doing a lot more highway driving, hence the higher MPG.

Another good point and perhaps a factor that goes against the more re-fueled Prius vehicles. The more high speed, non-stop highway driving that is done in a hybrid reduces the benefit of the hybrid system. I'm not saying that's good or bad, it's just the way it is. Also, as far as the Prius is concerned, the models with higher refueling will be the previous generation, not the more efficient 2010 models.

We don't have enough of the right kind of data to confirm any of this, it's just more of the factors that affect the outcome.

If anyone cares, I'll be happy to share the spreadsheet. It was kind of interesting creating the formulas to handle the copy/paste from Fuelly since there is no export.

[gabe1475]

The same goes for the Smart, MPG on the highway is in the gutter. The best mileage can be reached at 35-45MPH. Althought you can still get Mid 40s at 60-65 which is still not bad.

[rfernatt]

I dunno about 35-45 being optimum... 50-55 on smooth level ground seems to be best for mine.

Now, if I could just avoid hills (hard to do in WV), stops, and not divide the tank over 8-10 cold starts, I'd be in business!

[SylenThunder]

I have two friends, one with the Civic and one with a Prius. Both of them keep track of their fillups and both report numbers that look more like the green Civic line. For me, I see between 38 and 45mpg in my smart. Always fill with 93 octane BP, (except one tank I used 5 gallons of Mobil,) and I do not drive with fuel efficiency in mind most of the time. My best has been 48, and it was in the summer, on level roads with an average speed of 55-60mph.

I was keeping track on Fuelly, but got behind on transferring the data from my phone. Unfortunately, my phone LCD's got crushed and even though the data on the phone was intact, they would not copy my notepad to the new phone. As a result, I lost about 6 months worth of fuellings and haven't kept track of it much since. Was real proud of having a record of every drop of gas since I picked the car up. Now the failure of not being able to have that does not motivate me to keep it up.