66mpg? Is that all?
No, it isn't! I pulled it out to
72mpg! (or, just on the nice side of 4 litres per 100km)
(after adjustments - 38.85 mile round trip on 2.51 litres = 70.5mpg, or EXACTLY 4L/100km... buuuut, with a little bit of spillage out of both expansion pipe and filler neck because of a dodgy pump, and a few stop-starts between petrol station and m'way, couple very brief squirts up to 55 and another to 60 for safetys sake - think thats worth 1.5mpg extra..)
HOWEVER this required cruising at all of 45 MPH!!
Now you know what the buggers who hold you up on country roads at that speed are up to - getting major fuel savings
and b@ll@cks to all the wasteful types who want to overtake them! (they're retired - they have all the time in the world
) if i was to emulate them, i could maybe get all the way from birmingham to bangor on a touch over 10 litres (instead of what was my usual 18-20 or so), taking the A5 (and nearly 4 hours..)........ but collecting a whole lot of grief along the way
Despite the economy and the quietness, thats a very boring and somewhat antisocial speed and i dont think its worth the hassle for what, at that overall MPG, is a fairly fractional saving.... Even on the hills marked with a "slow lorries" sign, trucks had to overtake. Got a bit hairy when they came up two abreast from behind at a 10-15mph closing speed (on flat)... at least it was 2.30am when i ran the test so not too many people were affected...! (running down the hard shoulder for a couple miles proved this wasn't any less problematic - everyone assumes you're either drunk or stupid, rather than "experiencing engine and transmission problems")
It does however mean you spot their rear end probs and can flash 'em down - one parcel line artic went past with no lights on the trailer.. bit of main beam, hazards, horn, he pulls to the shoulder... 10 mins later overtakes again lit up and gives it the old indicator boogie
warm fuzzy feeling? hehe..
Overall 55-60 is a much better idea... slightly less frugal, but cheap enough, less boring, less waste of time (which in itself is "money"), less of a pain to other road users, and provides possibility of slipstreaming.
Funny thing - seems from these results that speed x economy roughly equals a constant... how very odd
.... 45mph = 72mpg.... 56mph = 57mpg (49mph=66mpg?!?*)... 72mph = 45mpg
.... 90mph = 36mpg or so?
(does kind of match up with the assumption that required constant power is a square of constant speed thru air, though.... so power over speed = energy used per unit distance (or, "gallons per mile"), and therefore, linear...)
Also did a second run going no high than 3rd gear to test the boring but mysterious revs versus throttle thing (a bit noisy in comparison, but at that "low" speed, no worse than mid-60s in top) to see if a high 5th would help (at 45 maybe not, but at 55-70 i *suspect* so)... havent yet got the lowdown on that, as i think turning up at the same petrol station three times in two hours in the dead of night would make the staff call MI6 on me
.. its only about a half mile from the house to the pump, so i'll just trickle on up in the "morning".
Maths during a very, very dull evening at work suggests a G40 top end would suit this car very nicely for 50mpg at 70mph with a wide but not quite floored throttle (say, 88%)...... the morning will tell more properly on that point...
If I can find someway to grow big enough balls to do it, and get myself a very powerful, long rock mix to play during the test (an hour or more end-to-end), I might test out constant 40 or even 35mph to see if dropping off the lower end of the torque peak means the consumption ends up climbing again (and again re-test it in 3rd, as that'll be right on the button revwise)... will deffo have to roll down the hard shoulder with the hazard flashers on tho. Or maybe take the toll road...
this little test showed up that my suspicions in the last couple days of a leaking tank and/or the engine's tuning heading south due to a rapidly plummeting fuel guage needle are ill-founded... think i might have been unknowingly pounding it a little more because of the more encouranging ass-support
* of course, working it out that way doesn't take into account the effects of slipstreaming, which neither tonights test (too slow!) nor the VW manual figures make use of - nor the 90mph one (too fast of course).... Even at 45, wind resistance is quite forceful - as opening the window and sticking arm out proved, as did the coolant temp needle barely being two or three degrees higher in 3rd gear compared to 4th, whereas when slipstreaming it shot up 20 celcius or more.
