Sunday drive 300km today.
Mostly back roads - lots of windy 100km/hr roads, with some good straights and some motorway.

Have to say the car - Blue... its been named LOL after wife's old horse ran great, the temp never got up to middle N or over, just sat at the lower part of N the whole day!
Anyway...
The trip meter said.. says...

Distance travelled 299.6km
Fuel usage 47.7l
Average Km / 100 k = 15.8L
Average speed 68.4km

Half way I filled up again, as you do in a V12 - and i added 37liters when the trip meter said we had used 32.5liters
My car has 16inch rims instead of the standard 15inch.

So based on all the above actual litres / 100km would be 18l / 100km
= 13US mpg

does that sound right?

 

Mmmmm,

Bit thirsty for a HE.

That is more closer to my PreHE monsters.

My HE's sat around the 12ish L/100K, on interstate trips, on cruise, and set at 110kph. Snuck up a tad when spending time stooging around towns on the trip, as you do.

Around the suburbs at home, 15ish L/ was about the best, and with 50KPH limits and stuff, OK.

If you "driving it" when you were able, then thats about OK.

Best mine ever returned was 11.2 over 25K kms when we cruised (HAHAHA) the OZ coast road over 15 months.

 

Different in a couple of ways but of interest.
had to drive my Xjrs (6 litre/ 4L80E) back from Queensland to Victoria last month, 2000 + klms 22 hours, computer says 9 litres/100klm
That was wrong, was closer to 10 litres.

 

The longest drive I had from the UK to Germany Had an average of 14l/100 km. In that were a couple of floored sections, topping out at around 250 kph... Otherwise it was around 130 kph for about 400 km. I used roughly half a tank (IIRC as it was 2013).

I think that was like 24 imp. MPG

 

I average 14L/100km on a 5hr highway drive including a sealevel to 4000ft climb over the mountains, atleast 120kph most of the way. Puttering around town of course burns abit more.

Mixed driving you should be able to squeeze 400km out of a tank, 430km the idiot light comes on.

Still good numbers for an engine that was designed 50+ yrs ago. My friend's 8speed turbo 2L lincoln SUV - same weight as the Jag - barely averages 12L/100km and this is supposed to be a ford eco-whatever direct injection blablaboost engine.

 

Which might account for some error. Or not. It's tire diameter that counts.

A bit low.

My '88 XJS would return 12 mpg (USA measure) in straight city driving. I would expect a bit better under the conditions you've described.

I remember getting over 20 mpg, as high as 23 mpg, under ideal conditions. Cruise control, flat roads, long distances which gradually inch the number upwards, driving very gently. Quite boring. Yuck.

Driving the car as it was intended to be driven would knock those numbers down in a hurry, making 16-17 mpg a more realistic average for highway driving. Remember, the natural order of things dictates that, when you have a V12 Jag, you're supposed to take your place at the head of the pack. Not dawdling along as though your Jag was made of glass, choking on the exhaust fumes of some snotty Audi or Bimmer.

Cheers
DD

 

On a long trip with cruise on, speeds anywhere between 120 km/h to 90 km/h ( 90 is the limit in the national parks) I could get 12.2 out of a 5.3, and it dropped to 11.5 L/100km in a 6.0 Around town driving in the 6.0 is around 16-17 L/100

 

Our Sunday drives average around 22 mpg (imp). That includes a bit of bad behaviour usually

 

Interesting - the trip computer said 15.8l / 100km but it had used a few litres more than what it said.
OK... just a minute... I filled it up and drove it hard home hitting 5,000 plus RPM for about a 15km drive were ever possible on open country roads - 2nd gear.

Then zeroed the trip computer when we went for our Sunday cruise so the 15.8l/100km might be accurate.
And believe me it was just a cruise on Sunday, little wifey does not appreciate me giving the car the berries.

Do others find the trip computer accurate?

 

Mine was very accurate. I checked the distance against my GPS unit and it was within 0.1%

 

I always found my TCs to be very accurate in terms of miles driven, versus the regular odometer. As far as fuel economy calculations, I'd say +/- 5%

Cheers
DD

 

My trip computer has failed, reads all sorts of nonsense, 4 gallon/second fuel consumption, clock stops working at 5:87pm. Never did find anyone able to fix them.

 

Yep, I've had no reason to doubt it.