I issue a challenge!!!

[SVOboy]

When I get a free day you can guess what I'm going to do with it. A trip to DC would be nice anyway. I'm hoping for 50 highway in my beast.

[diamondlarry]

a far more consistent method is to actually fill the tank right up the filler neck until you actually see the fuel level at the little metal flap in the pump "hole".

This is how I've filled up for years. It's almost an art to keep from spilling it on the paint though. I can usually, by shaking the car, get 1.5-2 gallons more into the tank after the first "click." I also try to eliminate as many variables as possible by using the same pump and pulling up to it in the same direction all of the time. Many people have said that this can cause the charcoal canister to get saturated but I've never seen a problem with that.

[MetroMPG]

Originally Posted by diamondlarry

Many people have said that this can cause the charcoal canister to get saturated but I've never seen a problem with that.

interesting - learn something new every day...

did some searching: overfilling the tank may put raw fuel into the tank vent line (on some cars the vent line connects to the top of the tank; on others it's at the top of the filler neck). if the vent system is filled with enough liquid fuel to saturate the charcoal canister effectively "blocking" the vent function, ODB2 cars will throw a code for Evaporative Emission Control System Malfunction.

neato. i've been filling my tank this way for 10,000 km on firefly#1 and firefly#2, and haven't seen any codes.

[Matt Timion]

Originally Posted by Compaq888

I would of probably achieved high 30's or low 40's if I drove during the day and not up the mountains.

I'll do the challange again but I'll change a couple of things. Most likely is pumping the tires up to 40 psi and driving 55-60. Plus I need to change the air filter.

Doubt it. Driving at night may have had some effect on your ambient air, but your warm air intake might have made up for the difference.

You also cannot blame the mountains for your mileage. You calculated your mileage going up and down the mountains. While your gas mileage may have been worse going up, I'm certain that your gas mileage going downhill was ridiculously high. I have gotten 46mpg going from Salt Lake to Southern California before, b/c the trip is almost a constant downhill trip.

If you want the best mileage, only travel downhill.

[JanGeo]

Nice to know that he ScanGauge is that close and I think it actually is because I went out for a longer ride today and found the gas needle still on the half tank mark for a few more miles like 250miles WOO WOO that puts me over 40mpg for sure and the engine is still breaking in as I drove today the mpg reading kept going up. I have 45.4 MPG average for this "half" tank of gas so far according to the ScanGauge. The speedometer speed on the ScanGauge was 2% low according to my GPS ant that I have adjusted so it may be a little on the higher side of the actual error of 1.5% - maybe I need to let some air out of my tires! Guys you do all realize how big a xB is right and to get this mileage is amazing as far as I am concerned. The best I have heard an xB getting is 39mpg.

I don't think there is any way to adjust the calibration on the odometer in the car unless there is some programming that can be done. What happens to the odometer if you coast with the engine off?? hummmm.

As far as fillups YES the gas charcoal filter can be damages if the tank is over filled - they say this in my Geo Manual 1994 but just drive after filling and you should be ok. Hot days are the killer when that 10 gallons + wants to expand it WILL! Definately keep clicking - the xB has the filler hose enter the tank about 1/3 the way down from the top so a big air pocket is there and I clicked for a couple of minutes. You should also really slow down the fill rate at the end to as slow as the pump can go to allow the air to come out up the filler hose from the tank. The Geo wuld be filled up to the tippity top and spill gas when I screwed the cap in ARG!!! A little side to side would release some air but it like being filled up hill. The xB should be filled down hill for sure - need to find an unlevel station.

[diamondlarry]

I don't think there is any way to adjust the calibration on the odometer in the car unless there is some programming that can be done. What happens to the odometer if you coast with the engine off?? hummmm.

I wish it were as easy to re-calibrate the car's odometer as it is the Scanguage.:-( When I coast with the engine off I have to turn the ignition back on once the engine stops so it will register mileage.

[JanGeo]

Sounds like it is controlled by the onboard computer but I would really like to have the odometer powered up by a button to I can read the mileage without having the engine running - kills (lowers) the MPG reading sitting idle after a trip . . . it does seem to like starting easier next time however. Just called brother again, there is a sensor usually on the tranny near the axle going to the left front wheel that runs the odometer and speedo and he thinks it is controlled by the computer. May be the odometer reading is a little low to compensate for tire wear and will be more accurate when the tires gets smaller and spins more per mile.

[Compaq888]

Originally Posted by Matt Timion

Doubt it. Driving at night may have had some effect on your ambient air, but your warm air intake might have made up for the difference.

You also cannot blame the mountains for your mileage. You calculated your mileage going up and down the mountains. While your gas mileage may have been worse going up, I'm certain that your gas mileage going downhill was ridiculously high. I have gotten 46mpg going from Salt Lake to Southern California before, b/c the trip is almost a constant downhill trip.

If you want the best mileage, only travel downhill.

You are forgetting that going down a mountain in an automatic makes the rpm go up under cruise control, which uses more fuel. Also the mountain has to be really downhill for the car to keep the same speed while not using the overdrive. Even if I let go off the gas while driving down a mountain the car still slows down. It's complicated but it's a lose-lose situation going down a mountain in an automatic.

I will find a way to surpass 40mpg on long trips. My tires are at 40psi and I plan to do the underbody really soon.

[Matt Timion]

Originally Posted by Compaq888

You are forgetting that going down a mountain in an automatic makes the rpm go up under cruise control, which uses more fuel. Also the mountain has to be really downhill for the car to keep the same speed while not using the overdrive. Even if I let go off the gas while driving down a mountain the car still slows down. It's complicated but it's a lose-lose situation going down a mountain in an automatic.

I will find a way to surpass 40mpg on long trips. My tires are at 40psi and I plan to do the underbody really soon.

I'm not sure I believe that. When I go down teh mountain in my manual in gear the RPMs are REALLY high. That's what engine braking does. The down side of an automatic is that the engine braking is always engaged when going downhill.

Odds are the engineers at Nissan anticipated this and made the injectors fire less frequently while going downhill.

I'm willing to bet that if you put a scangauge on your car and drove downhill your mileage would improve more than you realize.

[SVOboy]

Gas used is mainly factored between rpm and load. Higher rpm but much lower load = less gas used.