vicvega Posted June 22, 2017 Share Posted June 22, 2017 Not to be too obvious, but ... Using half a tank of fuel (9.25 gallons) over 237 miles is ~25.6 mpg. You're right. I meant 6 gallons. Whatever the case, I am happy with my milage. One of the main reasons I bought the car and if I get 25.6 city and highway combined I won't mind either. Sent from my HTC 10 using Tapatalk Link to comment Share on other sites More sharing options...
Ronin3.6R Posted June 22, 2017 Share Posted June 22, 2017 Ok not to beat a dead horse here but this does not seem to make sense. I have a 3.6 and cluster states 29 and I am calculating 27+ mpg. Now maybe I'm "optimum" in that I'm back roads 50mph all the to and from work. But for a 2.5 to get = or less mileage than a 3.6 is that accurate? There is a huge delta on the EPA ratings. I would think a main reason for a guy buying the 2.5 was he was willing to trade HP for economy? Link to comment Share on other sites More sharing options...
upstater Posted June 22, 2017 Share Posted June 22, 2017 Ok not to beat a dead horse here but this does not seem to make sense. I have a 3.6 and cluster states 29 and I am calculating 27+ mpg. Now maybe I'm "optimum" in that I'm back roads 50mph all the to and from work. But for a 2.5 to get = or less mileage than a 3.6 is that accurate? There is a huge delta on the EPA ratings. I would think a main reason for a guy buying the 2.5 was he was willing to trade HP for economy? same driver, same driving style, same drive, 2.5 will provide better fuel economy than a 3.6. The problem is when people pipe in, "Well I get XXXX mpg's" in my 3.6, while you only get XXX in your 2.5! It comes down to climate (down south you may not even see winter blends, you certainly won't consistently see cold half the year like in the north). The type of driving you do: long trips vs short trips, highway vs city, warmup vs no warmup, heavy acceleration vs feathering the accelerator. So yes, you can buy a 2.5 and drive it with no concern for MPG's and get less mpg's than a retired gentleman from Florida who feathers the accelerator on his 3.6. That does not mean if I had bought a 3.6 I would be using less gas for my commute. There is ample evidence of this, look at Fuelly and see the difference between 3.6 and 2.5 combined mpg's. Some drivers do better than others, but overall, you buy more gas for the 3.6 than you would if you bought the 2.5. That fuel is cheap and the cost is minimal or inconsequential may also be true, but that does not transform physics. Link to comment Share on other sites More sharing options...
ammcinnis Posted June 22, 2017 Share Posted June 22, 2017 ... maybe I'm "optimum" in that I'm back roads 50mph all the to and from work. You're also above 5,000 feet in elevation, which is significant. I have achieved an honest 39.4 mpg (calculated) in our 2015 Legacy 2.5 under similar circumstances ... Torrey, UT to Cameron, AZ ... but that is far from typical. You just can't compare one anecdotal experience with another, no matter how good the data. Under identical, real-world circumstances the 2.5 will always provide slightly better fuel economy than the 3.6, if for no other reason than that the 3.6 has higher friction losses (due to the two extra cylinders) and higher pumping losses (due to higher displacement). "If you don't know where you're going, any road will take you there." ~ The Cheshire Cat (Alice in Wonderland) Link to comment Share on other sites More sharing options...
Ronin3.6R Posted June 22, 2017 Share Posted June 22, 2017 Makes good sense. I was not pointing a finger at anyone. I just figured the difference would be significant and manifest itself across a wide range of terrains, altitudes etc. I was a little surprised that in some circumstances the delta is not very large like the ratings. I also expected worse mileage frankly based on the same data. Thanks for the clarification points... Link to comment Share on other sites More sharing options...
YeuEmMaiMai Posted June 23, 2017 Share Posted June 23, 2017 And that accuracy is way better than what the fuel consumption indication in the cluster is. More than that - it's consistent so you can compare your fill-ups pretty well, and also compare with other cars of the same model. The only way to get more accurate than that is to use a calibrated wheel trailing the vehicle. Even GPS units cuts some corners, so they can also have inaccurate measurements. source for GPS cutting corners? GPS is 100% math based and that is how they calculate your position. GPS is only inaccurate when you are stationary with no movement or you are in a area with lots of reflections. even when you are not moving, it gets you within a 35ft circle. Once you start moving it gets extremely accurate even when using WAAS as a correction source. What is the accuracy you ask? <= 8 inches. Your smart phone has a 12 channel GPS receiver built in and that will give you extremely accurate speed If you are using a RTK source your accuracy is within 1/1000th of an inch... when you are moving. Link to comment Share on other sites More sharing options...
Ronin3.6R Posted June 23, 2017 Share Posted June 23, 2017 There is a huge difference in accuracy of course between standard GPS based nav (like in a phone or car) and RTK using differential corrections. While standard GPS uses the "data" from the satellites etc. RTK uses the carrier wave. (Carrier phase tracking) Long story short, One is good within a few feet or yards, the other (RTK) down to a few centimeters. But big difference in cost and technology. The application (RTK) I support for instance will allow a self driven vehicle to go up to 20 miles, turn around and come back all accurate to within the width of a dime and is capable of using up to ten satellites for corrections. This level of accuracy is hardly needed to find a restaurant on a Saturday night but standard GPS as mentioned above is pretty darn accurate for almost anything a typical driver would need it for- nav, measurement, speed etc. Link to comment Share on other sites More sharing options...
ehsnils Posted June 23, 2017 Share Posted June 23, 2017 source for GPS cutting corners? GPS is 100% math based and that is how they calculate your position. GPS is only inaccurate when you are stationary with no movement or you are in a area with lots of reflections. even when you are not moving, it gets you within a 35ft circle. Once you start moving it gets extremely accurate even when using WAAS as a correction source. What is the accuracy you ask? <= 8 inches. Your smart phone has a 12 channel GPS receiver built in and that will give you extremely accurate speed If you are using a RTK source your accuracy is within 1/1000th of an inch... when you are moving. Just look at a GPS plot in high resolution and you see that the points are spaced in between and gives a direct line. Link to comment Share on other sites More sharing options...
YeuEmMaiMai Posted June 24, 2017 Share Posted June 24, 2017 that has everything to do with how fast your device gives you updates.. most consumer devices update slowly compared to lets say a Trimble AG GPS unit that is spitting out a minimum of 5 updates a second. we can go back and forth all day if you want but I know what I am talking about since I do Trimble support for a living. Even the most basic of smart phone with a GPS receiver will be FAR more accurate than the pulse counting sensor used in your car to calculate speed/distance... just for giggles I used my phone, my tablet and my dash camera's GPS to show speed and they were all displaying the same speed so yeah, I trust those over the car any day of the week when it comes to distance travelled and speed The phone a Lumia 950 uses a Qualcomm Snapdragon GPS unit. The Dell Venue 11 Pro uses a Sierra branded GPS and the Dash cam uses a Novatek NT96660 solution.... Link to comment Share on other sites More sharing options...
balbrec2 Posted June 25, 2017 Share Posted June 25, 2017 2015 Legacy Limited 2.5. 37000 miles on the clock. drove from Pittsburgh to Rochester to Syracuse and back to Rochester. 486 miles. Calculated mpg 35.2. Highway speeds usually around 73 mph. Cruise control most of the time. Still slightly over 1/4 tank left. Weather was mixed, some rain some dry roads. Avg. temp about 80. This car has great range. Link to comment Share on other sites More sharing options...
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