I recently got my 1986 XJS H.E. running properly and last week I took it on a fairly long drive. All of the drive was at high altitude (5,000 feet to 6,500 feet above sea level). Most of the miles were on the highway. But there was quite a bit of stop-and-go on the freeway, so it was more like city driving. Some duration of time was spent at 80 miles per hour velocity. The air conditioning was also running the whole time.


For the whole trip, the average fuel economy was about 17.5 miles per gallon. I do not know what is normal, but that figure seems reasonably good.

 

That sounds about right.

Back in my XJS V12 days I would get about 17-21 mpg on the highway using cruise control, 65-70 mph

I could squeeze a bit more if I drove very very gently...which isn't much fun.

I could get much much less if I enjoyed the car and the drive

Cheers
DD

 

Hi I usually average 17.9 mpg

 

OB US gallon a tad smaller than UK gallon 3.8lts against 4.55lts.

 

I am running 4L80E behind 6 litre and average 10.4 litres/100km. 27mpg local or 23mpg US.

 

Mine averages 15ishLtrs/100 kms in the Burbs, which have a blanket 50KPH speed limit.

On our round Australia jaunts we averaged 11.2L.100kms, which was for the total trip of 20000++kms travelled.

Quick blasts interstate usually sit on 12-13ltrs/100kma, dependig on the right foot angle, just as Doug said, its a V12, ENJOY it and watch where ya going, not the fuel gauge.

 

You're doing remarkably well to get 27 UK mpg.

I have '93 6.0L with same 4L80E transmission.

Driving on motorway at steady 60mph I once got 25 UK mpg .

Usually get 17 to 20 mpg cruising on motorway.

Stop start urban gives 12 to 14mpg average.

If I was concerned about fuel consumption I wouldn't have bought V12, as that's the main disadvantage to V12 ownership whether 5.3 or 6.0L.

Everything else about the car makes up for it. (In my opinion)

 

Mine is an '89 so diff is still 2.88, l assume yours is 3.54. That may be the difference. Brilliant cruising and slight disadvantage at takeoff does not concern me.

 

Back in my XJS days I used the car mostly for weekend road trips. It was nothing to knock off 600 miles on a weekend jaunt.

Out on the interstate or open road is where the XJS really shines. Utterly stable and relaxed at higher speeds. And, hey, let's face it: A *Jaguar* with *twelve cylinders* belongs at the head of the pack. Not the middle. Not the rear. Dawdling along, choking on the everyone else's exhaust fumes, is counter-intuitive.

Don't laugh but I often felt like 'king of the road' in my XJS. Others would see me coming in their rearview mirrors and clear a path. Seriously. No aggressiveness on my part, no horn honking, no flashing headlights, no fist shaking. The XJS has that kind of 'presence' on the road.

Cheers
DD

 

Even more so now l think Doug.

 

PERFECTLY said.

The XJ-S in V12 form IS the ultimate tourer, and 100% belongs at the front.

 

I get about 17-19 on steady running highway speeds. in my 86.

 

My car computer says I'm getting 21-25 on the interstate (1989 coupe).

In reality, I'm getting about 14. No running/driveability issues but wow, that's low.

Jess

 

V12 ownersship is still new to me, but I have now filled the tank 3 times, and the average numbers start to show a trend.
I pleased to se 17 US-MPG average overall. The usage includes many short trips (or just starting and manouvering cars in the driveway) and on motorway I normally settle at around 3200 RPM (2.88 diff). I guess that's around 140 km/h, my speedo needle averages thereabout...
I agree on the presence of the XJ-S. People get out of the way and less cars not pull out in front of me compared to driving other cars.

 

Now come on Leo.

That 2CV would get some awesome presence on the road, NO????

 

Mileage is better than presence for the 2CV. It's not too often I approach cars from behind in the fast lane, but it follows the traffic better than most people expect