The other day, I was watching my MPG decrease as I sat waiting for a signal change. I wonder how awkward it would be to shut the engine off at a lengthy stop, and whether the stop/starts on the engine would affect engine life. It would be nice if Jag offered a hybrid, as long as it was STONKIN FAST!

 

vacation trip

2847.5 miles

21.8 mpg

71 avg mph

basically 20 hours each way at 75-80 mph

6 days running around town

all in all I am pretty happy with the result

 

I was stopped due to construction and shut my engine down. It fires right up, but I don't know if I would make a habit of it. BMW has an automatic shutdown in its the 5 series and maybe others now. I test drove one. It's a bit unsettling. I supposed you get used to it. Everyone is questioning the wear and tear though.

 

That is a decent number. I have been running non-ethanol premium and I have been very pleased with the mpg. Running over 24 mpg on a 30 mph trip over the weekend. I wonder if the speed you were running at versus say 65 to 70 mph would yield better mileage?

 

I've had a few rental cars in the UK that had it (inc a BMW) and it is a bit unsettling, I agree. You do get used to it and it certainly impacts the mpg very positively in city driving. These were diesel cars in the main - are they more likely to stand the extra wear better than a modern petrol? Do the manufacturers care about long term wear? Surely they engineer something to last the life of the warranty plus a little extra to protect residuals?

 

I have run about 2 tanks of gas in a 2012 XF Base 5.0L loaner car. MPG is at 20.4 with mostly highway.

 

We did the same trip last week, but before we started our return trip, I had to put the temporary spare on due to a flat tire. Because of that, we had to make the 80 mile return trip at no higher than 55 MPH. Our mostly highway mileage was 30.2 MPG!

 

How many miles on the loaner car? My gas mileage has steadily improved over the last 3 months of ownership. I don't know if I attribute to the use of the non-ethanol gas of just breaking in of the vehicle.

 

5k miles on the loaner.

 

Road trip to California and return. Eleven days on the road to cover 3,422 miles (5,507 km). Almost all mileage was at highway speeds of 50 to 75 mph, 80 to 120 km/hr.

Instrument panel readout shows average speed of 54.3 mph (87.6 km/ hr) and bear in mind that most of Oregon and of British Columbia has a posted maximum of 55 mph or 90 km/hr......

Speedometer reading compared to GPS speed on my Tom Tom was 2 mph optimistic at highway speeds up to about 60 mph and then 3 mph optimistic from 60 to 75 mph. There is no fractional mph display on my Tom Tom as it displays rounded to the nearest 1 mph. I did not look at the GPS when travelling more than 75 mph...... . If I did ever reach any such higher speeds, that is, to which suggestion I make no admissions.

Instrument panel readout shows average fuel economy of 26.8 mpg (US gallons of course). Converting that to Imperial gallons which nobody in the World actually uses anymore gives you 32.18 mpg Imperial measure. That is 8.7 liters per 100 km for the reasonable people in the World using all metric units.

I purchased 133.71 US gallons of 91 PON gasoline and burned it all in this good cause. The only source of error would be the possible difference between the full tank when I left and the full tank I refilled to today. This must be less than half a gallon or two liters, probably much less. All intervening fills could have varied a lot ( though I know they didn't) and this would be irrelevant to the average calculation I have made.

Actual measured consumption based on delivery pump figures and my odometer is 25.6 mpg US. This is 30.74 mpg Imp. Also, this is 9.1 l/ 100 km.

The error between the computer and the physical calculation is 4.5% optimistic.

Bear in mind the fact that the inboard computer must calculate actual mass of fuel burned (from the ECU) and then display the consumption at a constant temperature conversion rate from mass to volume. I am pretty sure all North American fuel delivery pumps are volume corrected to 15C but I confess I forgot to note whether US pumps are volume corrected to the same temperature.

My point here is that the onboard fuel consumption computer may be corrected to a different standard temperature and if so this may account for the apparent error.

For a 4.2 liter (252 cu in) V8 driving a 4,000 lb (1800 kg) loaded with two passengers and a full trunk (boot) this is impressive fuel economy.

BTW, diesel prices in the US were about 15% higher than 91 PON gasoline. This means about 20% higher than the rotgut 87 PON gasoline most North American engines run on. Wonder why diesel cars don't catch on over here?

 

I purchased my XFSC last week in Denver. I flew in and drove back to Phoenix. The trip was 926 miles according to the trip computer I averaged 22.8 mpg and 79 mph. I kept my gas receipts and I used 38.985 gallons of gas which cost me $158.65. My actual mileage was 23.75 mpg. I did see triple digits several times but spent the majority of the drive with the cruise set at 92 mph.

My first tank of city driving gas was 16.5 mpg based on the trip computer but the car spent most of that tank in dynamic mode :-)

 

I just beat my old MPG record of 28 MPG with - 28.5 MPG on a 92 mile trip - 54 avg MPH.

 

I only have had my XF for a month but I bought it 300 miles away from my home and ave already taken a 300 mile round trip two weeks ago so I have a good highway figure.

Normally I drive about 40 miles a day. I drive about 50/50 city/highway to work everyday and average 23-24 mpg and I do not baby her. On highway trips, average 75mph, I am getting 27-28 mpg.

I bought it with 35k on the odo as a CPO and am thrilled with the gas mileage.