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On a recent trip from San Francisco to Anaheim and back, I noticed a pretty cool thing that I thought I would share.
My 2003 XK8 is over 20 years old now, gets driven regularly and has nearly 175k on the clock. She isn't perfect by any means, but she is mine and I love her.
To see the average fuel consumption hit over 25 miles to the gallon when the spec was 23-highway from the factory, is a sight to behold on a car with as many miles as mine has. Not sure if this is unique amongst XK8 owners but it made me smile for sure. Big old honking V8 after 20 years, exceeding the factory spec for fuel economy is pretty cool.
That’s pretty good indeed. And mirrors my best very closely. In the thin air of the plano alto’s of northern New Mexico I could get 25-26 mpg on the highways.
But normally my average Highway mileage is 21-23 mpg and 10-14 city mpg.
I know that lower than most, but my lead foot is mainly to blame, and to a lessor degree, the “sport” switch, which is always set to “on”.
On highways I regularly see 8 litres/100 kilometres which is 29.4 miles per US gallon in our 216,000 kilometre (134,000 miles) 2003 4.2 XK8. Strict speed limits in Oz of course with max 100 or 110 kph in almost all states.
On highways I regularly see 8 litres/100 kilometres which is 29.4 miles per US gallon in our 216,000 kilometre (134,000 miles) 2003 4.2 XK8. Strict speed limits in Oz of course with max 100 or 110 kph in almost all states.
How strict ?
what’s the likelihood you have ever gone over 110 kph ? Is the penalty worth it ?
I am surprised the wide open spaces of the Australian interior have any speed limits.
Personally, in the XKR, I chicken out over 131 mph, roughly 211 kph, as my reflexes aren’t what they used to be. The car was certainly ready to go faster.
I only ever took my XKR up to 130 mph or so, I also chickened out. I average about 22.7 mph UK gallons but driving long distance I managed 34mpg once somehow although I've never seen that since. 24-28 is normal on a long trip up to Scotland. But normal driving with a bit of fun about 20-23 mpg is to be expected.
It has been many years since I last checked the gas mileage on my wife's 2006 XK8 but back when I did so, it easily reached 30 mpg on the highway with her keeping the cruise control set to 72 mph during her long trips back and forth to Florida to visit her now-deceased parents. I never bothered to check the around-town gas mileage....
"Fuel economy" is kind of an oxymoron when it comes to these cars. I have gotten great mileage on my XKR as well as the car it replaced (1995 Corvette) but ONLY when doing extended driving on open freeways. On the typical day-to-day street driving both vehicles get 12-15 mpg. On a tangential note since the wife and I replaced the "decent car" (her words) which was a 2012 Acura TL with our 2024 Lexus NX350H, I have been obsessed with how much mileage that hybrid gets and it is the opposite of non-hybrid vehicles. On the routine street driving we get up to 50+ mpg but on the freeways it drops down to maybe 38 mpg.
Anyone know the history of the divergence of the UK and USA gallon measurements ???
I read where the USA gallon is based on the “wine gallon” and the UK or Imperial gallon is based on the “ale gallon”.
That explanation doesn’t tell me much.
Z
"The gallon originated as the base of systems for measuring wine and beer in England. The sizes of gallon used in these two systems were different from each other: the first was based on the wine gallon (equal in size to the US gallon), and the second one either the ale gallon or the larger imperial gallon."
"The Queen Anne wine gallon, defined as 231 in³, which the US uses for all liquid. (In metric, it is 3.785 411 784 L)."
Nothing much changed around here since Queen Anne.
I get around 14/15 mpg locally, which may be atypical due to the road system. I was pleasantly surprised when I did the first French trip with her, as consumption improved to around 25mpg.
We don't run Jaguars because we're fuel-economy conscious...
FYI, The 2003 XK8 with 165K miles averages about 27-28 MPG (US gal) on interstate trips. Speeds at 70-80 MPH. I record mileage and number of gallons at fill up. Miles divided by gallons equal actual MPG. The digital read out is optimistic so of little use to me.
I have a 2002 XKR with the 5 speed and 45K miles on it, and I average 15-16 US MPG mixed urban/highway driving... best I've ever gotten was about 25 mpg on a long highway run. Sitting at lights kills economy in these cars. Well, that and booting it. The 6 speed/4.2 combination does make a significant difference.
I will note that since I changed my upstream O2 sensors I actually get 2mpg better economy than before. Been tempted to get a new MAF as well. AFAIK hte downstream sensors don't have any input on fuel trims and are used for emissions monitoring only (and thus why they are not present in all markets).
”…….Been tempted to get a new MAF as well. AFAIK hte downstream sensors don't have any input on fuel trims and are used for emissions monitoring only (and thus why they are not present in all markets).
if you do get a new MAF sensor be sure to get the one for the 4.0 XKR (or XJR). The XK8 is not the same , and that’s a shame as it’s used in many different cars and is much cheaper.
i tried several budget MAF sensors that were advertised as being correct for the XKR, and the car ran horribly with them. Finally I found a proper XKR sensor (Denso) at a slight discount from a Jag dealer and all was well
if you do get a new MAF sensor be sure to get the one for the 4.0 XKR (or XJR). The XK8 is not the same , and that’s a shame as it’s used in many different cars and is much cheaper.
i tried several budget MAF sensors that were advertised as being correct for the XKR, and the car ran horribly with them. Finally I found a proper XKR sensor (Denso) at a slight discount from a Jag dealer and all was well
Z
Interesting; I got proper denso O2 sensors for roughly this reason (plus changing them is a $%^& and didn't want to chance having to do it twice) so I'll be extra careful if I do - I'd seen mention that the MAF was shared with some Mazdas, but evidently not for the XKR.
On Fuel Economy
