I was wondering if anyone could shed some light on the Range number we get after a fill up (miles till empty). Is it strictly a volume measurement, or would gas quality register immediately (meaning would retarding or advancing the timing depending on gas quality come into the equation for calculating the range)?

Other than that, anyone have any gas brand preference for the 4.2 V8 NA in the XF? Performance or mileage related. Especially if you're in Salt lake city (craptacular gas), but pleae chime in wherever you are in the country.

Thanks in advance.

 

Range to empty would be calculated from the fuel economy average since the last time the trip computer was zeroed and using the fuel sender for fuel quantity. It is an approximate number no matter how you look at it.

This number is updated by a software program which takes the rate of fuel use from the injector cycles as measured in the ECU and computes the fuel level from the tank sender and averages these out to compute a range prediction.

Fuels with more ethanol tend to give higher fuel consumption (lower mileage) numbers because ethanol has less energy per unit volume. High elevation fuel supplies tend to have less octane improvers (less ethanol) as these are less necessary at high elevations. Winter fuels have more ethanol than summer fuels.

I have found Shell gasoline to be superior in my location near the mountains of Western Canada, at 3,300 ft and higher.

 

My car (same engine) likes Shell brands over the others that I've tried on a regular basis - Texaco, Mobil, Exxon. Must be that nitrogen!

 

Thanks for the replies guys. I was using shell in my old car and it was superb till they switched to the nitrogen enriched formula, the performance was very noticably affected (and not in a good way) and my MPG dropped by 10%. It's the only shell station in town so it may be the station cheating the 91 having it mixed with lower grades, plus I've already tried it once. I don't think the car liked it at all. May have to try it for a few cycles see if I was just being biased from prior exprience.

I switched to philips 66 (another top tier) and got my MPG and performance mostly back on my old car. It just wasn't as good as the old shell formulation. I guess I have some experimenting to do. Going to compare the 3 comon brands I've used Shell, Chevron, and 66. I'll update/post what I find for the salt lake area.

 

Oh, only 91 octane? I only use the 93 at shell, if its less, I move on.

 

Yup the most you can find around here in salt lake is 91. High altitude 4000ft, so engines are less prone to knocking with lower octanes, and just because the gas companies are a bunch of miserly SOB's (excuse my language)

 

[QUOTE=peniole;152142]it may be the station cheating the 91 having it mixed with lower grades,

There are only two grades 91 and 87. The mid grade is created by pumping half from one storage tank and half from the other.

I also suspect some of my stations of cheating and putting some 87 in the 91 storage tank. It would be very easy to do and the profit margin would be huge, 12 cents per liter in Canada which would be around 35 cents a gallon US. The retailer would show a throughput of 87 and pay the supplier for it but charge the customer at 91. However, each pump should have a meter sealed by the government so the volumes of 87, 89 and 91 would not match the pump meters....

 

My 2011 XF Premium really likes BP Ultimate, consistantly gets 27.5 mpg at 75 mph, however, on a recent trip to Montreal I had to fill up with Shell containing 10% of either Ethanol or Metanol and my mileage dropped to 25 mpg.