Hi All,

I know people are going to tell me that if I am asking this question I probably shouldn't have an XK8, but I have got one, so its a bit late now.

The official numbers claim 18mpg when I looked it up before purchasing. I was told by the chap who sold me it to expect around 16mpg.

I drive to work daily in my car and it is urban mileage, but most of the journey is on an uninterrupted stretch of 40mph road that I have always got good mpg on in other cars.

It does seem my actual mpg is much closer to 10-12mpg than 16 though! I drive with featherlight acceleration, so I am wondering if slowly accelerating is causing me to drive at higher revs for longer than just going up to speed straight away and letting it run at 1200rpm for longer?

Advice is welcome

 

No way it should be that low. You need to check for codes and monitor fuel trims. There are several code readers you can buy that will do this. Check in the Sticky's for code readers recommendations, and do a search for fuel trims.
Something as simple as a thermostat stuck open can ruin mileage, also. Does the needle get to center?

 

I've also been having some wonky mileage. Last time I checked, I get about 25 mpg highway, but I'm getting 14 mpg city.

You can see why this is a problem? The solution I'm considering is getting a bike for all of my local city commuting.

 

IMHO, comparing city MPG can be very inaccurate due to such a wide variance of speeds, stoplights, traffic jams, etc. My "mixed" driving in city and highway = low 20s MPG. But I don't live in a city that has traffic jams or gridlock.

However, highway MPG lends itself to closer comparison … unless you're running triple digits on the autobahn.

Long trips at 70 to 75 MPH should return USA MPG in the upper 20s.

 

When comparing fuel consumption from members around the World, it's important to take the difference between the US Gallon and our Imperial Gallon into account.

I've kept fuel and mileage records for years on all my cars. Over the 24129 miles I drove in my 2001 XK8 4.0 litre, it averaged 20.31 mpg. This was 50/50 urban/motorway and I don't hang around on the open road!

If you want to monitor driving style against fuel consumption, set your trip computer display to 'Instantaneous Fuel'.

Graham

 

Mine is a daily driver and I probably do ~80% city stop & go against 20% highway time. I average about 18 mpg. I can put it in sport, drive more aggressively in the city and still get 16 mpg.

So I think you have some other issue if you are getting only 10-12mpg. Is everything else OK? No codes? No running or idle issues?

 

I get 24 mpg highway at 75-80mph. In my mixed driving I get 15-18mpg. As for those saying that you're way too low I disagree. I get 12-14 in my 2 mile to work, 2 miles to the gym then 2 miles home daily commute. In the XJR I get single digits doing the same, on my Triumph Tiger 955i I'm lucky if I see 25mpg in the same commute.

 

I get 27mpg for all highway driving 70mph with air con, 22mpg in mixed use city/highway.

 

Hi Graham, I suspect you quoted US Gallon?


During the summer, I was averaging 26 UK mpg (21.7 US mpg). With the cold days, the mileage has now deteriorated to a 22 UK mpg in average (18.3 US mpg). ~70% road and motorway, 30% urban. Quiet driving style with a few furious accelerations.


I always noted an increase in fuel consumption in the winter, for all the cars I had so far (petrol engines only).


Many thanks

 

We are currently getting 15 around town,25 or 26 highway,her daily driver.Lots of variables to that question though,tires,pavement,weather,temp,etc.:icon_santa waving:

 

1100 mile round trip to Ohio we averaged 26.2 mpg average speed was 76.5 mph. Wife's Buick only gets 24.3 mpg. and not asuch fun to drive! Jim

 

Hi Crimsonsphinxs, welcome to the site, I use my car to get to work sometimes, Work in Elsham live in Grimsby and also a bit of town driving and average 26 MPG. Have you seen the censor working on your location LOL.