Last post on May 12, 2013 at 5:09 AM
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Chevrolet Cruze, Car Buying, Car Leasing, Sedan
#74 of 134 Re: 2011 Cruze Eco 6MT [drvette]
Nov 14, 2011 (2:50 pm)
Oh I am very aware of the optimistic nature of the computer generated mpg LOL... I hadn't noted (or reset) my trip odometer so I don't know how many miles I actually travelled on my first tank of gas. I am on my second tank now (about half a tank gone so far). I drove the family up to the wine country (Sonoma CA) and averaged ~40-41 mpg round trip (including going through downtown SF both ways). I will likely fill it up this weekend, so I will have a much better idea of how optimistic my computer is. I had a Mazdaspeed 3 prior to this car and the computer was off by about 2-3 mpg (~10%). I generally use the computer as a relative gauge to my mileage and actual "pen and paper" for my real MPG.
My "normal" commute is about 2/3rds City and 1/3rd Hwy, so I am targeting 33 mpg-ish as my goal.
#75 of 134 Re: Computer shows optimistic MPG ! [drvette]
Nov 16, 2011 (3:48 am)
Dr Vette, the EPA tests are not fooled by the dashboard mpg display.
My Cruze's dashboard average-mpg display seems to be within 1mpg.
Your dealer may be able to recalibrate yours.
(If not, maybe take note of how inaccurate it is and subtract the proper percentage - you will probably find that it is a fixed percentage.)
#76 of 134 Re: Computer shows optimistic MPG ! [drvette]
Nov 16, 2011 (2:24 pm)
Well I just filled up. Now it was not at the same gas station, so there are bound to be some minor fluctuations, but I travelled 333 miles on 9.0 gallons of gas 37.0 mpg. The computer stated 40.1 mpg, so it is off roughly 3 mpg on my car (which has been my experience with out Lexus and my previous Mazda). I do add about 4/10ths of a gallon after the initial shutoff... I wonder if this confuses the computer at all...
My driving had a lot more freeway driving than normal so I expect my average mpg will be a bit lower going forward.
I love my car. I cannot wait to take it on a longer road trip to see how close I can get it to 50 mpg
#77 of 134 topoff gas -> reduce mpg
Nov 20, 2011 (5:11 am)
adding gas after the initial shutoff can wreck parts of the evap system, which could significantly reduce gas mileage. there will be no confusing the dashboard mpg function about that - instead, the OBD function may throw an error code after enough miles/tanks without evap/gas-vapor-recovery system functioning properly.
A manual way to know vapor-recovery system can be functioning properly is when you open the cap when tank is fairly full and hear whoosh of air. Whoosh = good. When tank is nearly empty it might not whoosh as much , or at all, however.
if plenty of gas in tank and it's been sealed for a while especially with some temperature changes (especially temperature increases), THEN
if no whoosh, that means no positive pressure in the tank, and evap system cannot function in that case. If yes whoosh, the vapor-recovery system can work if the charcoal canister hasn't already been wrecked by being flooded with gas too many times.
#78 of 134 Re: 2011 Cruze Eco 6MT [drvette] *Update*
Nov 24, 2011 (8:19 am)
For "true" accurate mileage distance readings, travel an interstate highway for 10 miles while setting the trip meter at the start.
On one of my vehicles, the "indicated" distance was 10.3 mi though only 10 actual miles traveled.
So I subtract 3% from the miles traveled "prior" to figuring mpg figures.
I travel from Ga to Colorado rather often and use a 100 mile run to get a super accurate figure, just FYI
It seems as if most vehicles are a bit optimistic on the odometer, trip meter and computer, even on new tires of correct size ? Go figure.
#79 of 134 Re: topoff gas -> reduce mpg [elias]
Nov 24, 2011 (8:23 am)
I agree this can flood the charcoal canister with fuel which will be sucked into the engine.
However if All things are working correctly, the O2 sensor should read this and lean the mixture accordingly. [After the engine is in "Closed-Loop" mode,
[proper eng temp and O2 sensor fired off]
#80 of 134 Re: 2011 Cruze Eco 6MT [drvette] *Update* [drvette]
Nov 24, 2011 (12:21 pm)
For "true" accurate mileage distance readings, travel an interstate highway for 10 miles while setting the trip meter at the start
I like your idea. How were you able to test the "true" mileage vs the odometer? Did you use a GPS, Mile markers...?
For what it is worth, I just filled my second tank almost all city driving (170 miles city, 10 miles of highway), and I averaged 29.9...the computer estimated 30.1. The gallons used on the computer was exactly what I put in the tank...so I guess the rest is just rounding.
Happy Thanksgiving to All in the Forum!
#81 of 134 Re: 2011 Cruze Eco 6MT [drvette] *Update* [drvette]
by kyfdx HOST
Nov 24, 2011 (2:36 pm)
That's a huge variance for an odometer..... are you riding on the stock size tires? Speedometer variances are common, but odometers are usually within 1%..
I'd be really ticked if my car read 51,500 miles, when I'd only driven 50,000.
#82 of 134 Re: 2011 Cruze Eco 6MT [drvette] *Update* [drvette] [garv214]
Nov 25, 2011 (12:41 pm)
I use mile markers not GPS, don't have one at this time.
On my many trips to Colorado from GA, I often check the odometer for a 100 mile run.
#83 of 134 Re: 2011 Cruze Eco 6MT [drvette] *Update* [drvette] [garv214]
Nov 25, 2011 (12:43 pm)
Forgot to mention that a Computer Trip indicated 30.1 vs an actual 29.9 is what I'd call "accurate, enough anyway.