[john 070]

My '98 Maxima is on steroids. Suddenly 2-3 mpg more than before, nuts. I have tracked the mpgs for 16 years, so I do have a sense of what they should be. It's crazy, my commute to work now yields about 23.x. It has been 21.7 for 4 yrs. The 23+ has been consistent since July, that's over 3 mos. and tankfuls. Going to DC and back yielded 30 mpg. What? It did do that in 1998-200x, but not within the last 5 years.

What may be the culprit is replacement of 1/4 02 sensors which are all original. Knock sensor also got replaced but I doubt that's it. PCV and some hoses were also replaced (leak?) Life can be unpredictable.

 

[Hersbird]

I have always run every car and truck I own till the light comes on or more before filling up and only on a 20 year old Chevy Beretta have I ever had to replace a fuel pump. I almost always buy used and high mileage on top of that.

 

[Rolltide#1]

I've read that the Enclave owner's manual recommends resetting the mpg calculator at every fillup for more accurate results. Resetting the mpg calculator at every fillup makes little sense unless you want to know the mpg for a specific trip or condition. You may have made a change to your car, new tires or spark plugs, i.e., and want to see what difference it makes. If you are wanting to see your mpg in city driving or highway driving only you might reset the calc and check your mpg for that time period only. Leaving the mpg calculator alone results in an average spanning over several fillups. That is the actual mileage that you have been paying for. It includes city driving and highway. This is true for any make and model of vehicle. BTW, when you reset the calc don't pay any attention to it for the first 20 minutes or so. You will see ridiculous numbers at first, especially if you idle a lot or go downhill at first.

 

[rbarrios]

If you have Onstar App, it will show you the Lifetime MPGs of your vehicle.

 

[Emmen]

I get about 11 mpg around town and 18-19 at 70 mph highway on my FWD. Tracked it carefully using both car and fuel pump and odometer. Tried everything I can think of like air filter and injector cleaner. Doesn't work.

 

[cfedor]

I get about 15/16 in town and about 20/22 highway. Just what it is indicated to get for an AWD trim level.

 

[ckgrabert58]

I have a 2009 Enclave that I use middle grade gas and have rebuilt engine, replaced 2 O2 sensors and fuel pump. I get 16.9 to 17.1 mpg for both city and highway. I even tried using Lucas gas treatment and can't get over 17.1 mpg. After replacing the second O2 sensor it went down instead of up to 16.5. I only get gas at BP or Marathon. No engine light after replacing O2 sensor. Once I get over 70mph it's sucks gas. Anyone have any ideas what else I can do it's horrible on gas.

 

[JayS]

Start by going back to 87 octane. That's what our cars call for, going up does absolutely nothing except lighten your wallet faster.

Paying a Premium for High Octane Gasoline?

Higher octane fuel is not necessarily better for your car.

www.consumer.ftc.gov

.

What about your tire pressures? Low tires can make a big difference.

Hauling around a lot of extra crap in the car? More weight = less MPGs.

Got a roof box or something else adding drag? You'd be surprised how much drag a ski box can create at 75mph.