Just curious what the best miles per gallon, mpg, you got. Also post your Average miles per gallon if you want.

In your reply, please post:

US or Imperial Gallons

Year model

V12 or 6 cylinder

Manual or Automatic transmission

Any modifications you made to your car which may have changed your fuel mileage. For example, changing the final drive ratio.

 

1988 XJS Coupe 5.3 V12


The *very best* highway mileage I ever got was 23 mpg. That was a 200 mile or so trip where I was forced to stay close to 60 mph.

More typically I got 18-21 mpg on the highway.

USA gallons, by the way. You know, the real ones. Not those silly inflated imperial type

Cheers
DD

 

23mpg!? That's too good!
Mine is '92 5.3L V12, facelift, 17mpg(US) after 1300km travel is my best. Maybe I am not patient enough :P

 

16.16L/100km for me over 1900km of largely just commuting. And those are imperial kilometres and litres... Or are they US? I get confused.

I'll caveat that though, as my car has had the diff ratio changed, which causes everything to under read (speedo, odo, trip computer). So based on my actual kilometres done I'd say I could probably drop that figure by around 10% down to 14.5L/100km - not bad for a thirsty old beast, but the 5-speed conversion is undoubtedly saving me a few litres. Now if I could only resist hearing that incredible sound I might be able to get it down to Prius levels!

(Based on some quick googling, 14.5L/100km works out at 16.2mpg or 19.5mpg depending on how big you like your gallons)

 

26 mpg on the AJ16.

All highway.

 

On the trip from Britain to germany: 13.6l/100km

V12 noncat automatic

 

16mpg for me. 85 5.3 V12.

 

24.5 US mpg in my 4.0L 5-speed, averaged over two thousand miles last summer. No trips over two hours of two-lane black top.

 

I used to get 18-21mpg around town when I lived near atlanta because so much of the road was 55mph, which is a good speed for the XJS with few enough lights.

Now I live in tallahassee with 4 million traffic lights and the speed limit is typically 35mph, so I hover around 12. Last time I counted it was 9, but I was having some fun.

I still spend less in gas because everything is closer together though.

I would be super interested in seeing the return on a 6 speed in a v12. One of the setups from driven man I saw once put 6th gear at 90mph at 1500rpm!

 

'85 Coupe V12 5.3

Larger throttle discs, 16CU ECU, NO cats, NO emission junk, cold air intakes, 2 1/4" exhaust ALL the way to the rear tips.

11.2l/100km (25+MPG Imperial) for the last round Australia drive which took over 12 months and 20000kms approx. LOTS of flat out running, by that I mean 5500rpm for hours on end, then dirt/mud/rain the next day and down to 50/60KPH most of that day. So a good mix I think. Air con on for 90% of the trip. Car fully loaded, as I am yet to find a wife that travels LIGHT, damn.

Around where I live and at 50KPH speed limited, about 15+l/100kms (18MPG Imperial).

1976 PreHE S2 V12 5.3 (Sir Arthur), stock as a rock, has the fuel gauge moving faster than the tacho no matter how you drive it. Never worked it out, never saw any need to scare myself more.

 

Just on city driving I was quite surprised on the mileage I just calculated. Came out to about 12.7 MPG

 

when i bought my xjs i drove it about 1300 miles home. my best tank was 26mpg, worst 23mpg. other shorter highway trips have been in that range as well. mixed driving is typically just under 20. all city driving with playing a bit closer to 15.

1993 xjs convt. 4.0L auto.

 

My best with 1992 XJS V12 is 22.3 miles per Canadian Gallon stock air intake. I has seen where it can be increased by up to four miles per gallon if one eliminated the standard tubs and went to a wider air intake and clean filters. I plan on doing that for next summer once I decide the pipe routing.

 

Best gas mileage has been cruising the back roads in southern Utah
50 to 55 mph at 24 miles per gallon.
Speed limits in southern Utah on freeways is 85 mph.
Cruising at 90 mph mpg drops to 16 mpg.

 

'89 XJS w/5.3V-12, currently 102,000 km

-Just got back from 1200 km weekend run, 21.9 av miles/IMP gal. This is very close to my overall mileage, have seen 22.4mpg, but that was running approx. 85km/hr only
I burn Hi-Test (92oct), 3 out of 4 tank fulls.

 

95 4.0 coupe AJ16 automatic


Best highway on two 500 mile trips 21.5
Best in town commute average about 15-16, unless it's bumper to bumper then it drops to 12-13.


But I am a "little" agressive

 

1992 XJS 5.3 v12

The very best mileage was on 2000 mile trip on highway
18.4 MPG US

Jeff