It's on! aka the mpg challenge aka surprising results

[Tahrey1043]

First of all I think I can let the pictures (and my sig) speak for themselves


Sweet-as The smart, prius, and civic EMT can eat my face

May not be able to afford a pump-duse diesel yet, but i think a petrol 1.0 litre can be a suitable alternative for now.... it just requires self control
(of course its lacking a bit on the power side!)

Outbound trip, inspired by article in autocar on the ultimate diesel mpg challenge... sticking to the limits all the way, and a constant 70mph (4000 revs!), with some 40-60 variable limits made up for by getting lost on bham/london suburban streets, and no fuel saving "tricks" gives a surprising 47.5mpg... and wasn't too much of a slowdown from 80-90 in the end, especially with the traffic.

Inbound, keeping 55-60 on a pure direct route, and slipstream "stalking" trucks where possible (and coasting.. not much though).... 66.0mpg! Was well chuffed with that, particularly as the official figure is "only" about 55 at that speed (vs 41 for 75mph..). Made it a very cheap way of getting about, and not any slower than taking the train or a coach. Reduced the average annoying slowdown to mere periods where suddenly everyone was going at the same speed as me Though I must say driving to keep the artic in front at a screen-filling but "safe" distance is a very odd affair... plus i discovered a way of telling when you're *in* the stream - engine temperature rises dramatically! (not surprising, given that suddenly you have maybe a 10mph airflow for a 3000rpm "idle")
Wasn't all that boring in the end either, at least with enough new discs to go round - and the occasional fast-closing BMW lunatic to dodge when doing 55 in the left lane on an empty stretch (they don't seem to notice slow cars anywhere near as soon as trucks, or pull out to the middle lane more than 10 yards before impact - brown trousers time)... and at 3 hours for 170 miles, not too much slower than last time i tried to blast the route.

Interesting little experiment that, and saved at least £15.. or the price of getting 5 tyres balanced will have to see how this next couple weeks of using it mostly for trucking back and forth to work (pretty much full time all of a sudden) at 35mph with mucho coasting...... and just how much low-speed tedium my poor brain can take before I HAVE to go for a quick blast or three.

(if only i got that 5-speed, it could have been 50 and 70 ... ah, dreams)
(mmmm, try similar in a hybrid diesel.... triple figures?)

[Gareth_GT_Hatch]

Dude thats impressive. I dont want to get into a long convo about gearboxes again but a 5 speed 1 litre box wouldnt have seen much improvement. You certainly couldnt have gone alot faster than what u were doing.

The best I got out of my blue GT which was standard at the time apart from being de-catted, was 49mpg and that was the journey to and half way back from inters (380 miles) and I used something like 35 litres. I wasnt dawdling either, 60-90 all the way there but probably averaging at about 70. It was appalling weather too which meant I had all my wipers and lights on (it was dark as well). Also when I got there I had my lights on full beam with the engine running so I could put my tent up. Anyway, I dont think I could ever beat that tho. :insert clappy hands smiley here:

[Tahrey1043]

not bad at all for 70

i wasnt thinking in terms of speed with the 5-gear box tho.... more in terms of...

-------- 56mph ---- 62mph ----- 70mph
4spd 3200 3500 4000rpm
5 (GT) 3000 3300 3750rpm
5 (8P) 2650 2900 3300rpm

So a GT type one would have given me a little more economy, and the 8P allowing me to basically sit on the torque peak without *too* wide a throttle setting while following the trucks (=best use of fuel per stroke... allegedly)... and getting similar revs at 70 as i was when slipstreaming with the current one.
a pipe dream, anyway...!

(as for that whole throttle setting thing, i now see what the point of wide=bad was - more air going in means more work going in to compression etc... then (yet) again is that enough to counter the higher revs at a smaller opening?)

see, i can be brief-ish sometimes

[Gareth_GT_Hatch]

I dont want to get into a long convo about gearboxes again

[Tahrey1043]

wasnt going to start one, just explaining myself in response to

You certainly couldnt have gone alot faster than what u were doing

is all

[Gareth_GT_Hatch]

I know, but I said this originally:

but a 5 speed 1 litre box wouldnt have seen much improvement.:

And non of them boxes u mention are the 1-litre boxes. The AFA has the same 5th as ur 4th and the ahz has a slightly longer one. You would need to do 200 rpm less to do 70 which is quite a bit I suppose, good for at least another 3mpg. I really dont know how having the gearbox from a more powerful car would affect performance or indeed economy. An AHD box would be ok but Im not sure there would be much if any "go" from an 8P. Its ok to dream though.

Ive opened a can of worms now *here we go again*

[The Drummer]

Well done, that's impressive! I find it hard to get good mpg out of my runner as, dare I say it, it's an auto...... Anyway, I tend to drive at 55 - 60 everywhere to try and save fuel, as it's not particularly quick, and the instant you put your foot down, wave bye bye to the fuel! Any tips would be handy! I normally get about 310 miles to a tank (it's a 1.4) costing about £25 with 35 litres of fuel. Apart from that my knowledge of working out mpg is limited. I don't think it's too bad though.

[bstardchild]

Well done, that's impressive! I find it hard to get good mpg out of my runner as, dare I say it, it's an auto...... Anyway, I tend to drive at 55 - 60 everywhere to try and save fuel, as it's not particularly quick, and the instant you put your foot down, wave bye bye to the fuel! Any tips would be handy! I normally get about 310 miles to a tank (it's a 1.4) costing about £25 with 35 litres of fuel. Apart from that my knowledge of working out mpg is limited. I don't think it's too bad though.

Bout 40 mpg

How to work it out

Miles (310) / Litres (35) x conversion factor (litres in a gallon = 4.546)

There you go - Job Done

Trick for accuracy is to brim fill from a pump ( full bore fuel insertion till it clicks - then no more) travel distance and then brim fill again to the same process and on the same pump at the same garage.

Use calcualtion above

IHTH

[bstardchild]

Inbound, keeping 55-60 on a pure direct route, and slipstream "stalking" trucks where possible (and coasting.. not much though).... 66.0mpg! Was well chuffed with that, particularly as the official figure is "only" about 55 at that speed (vs 41 for 75mph..). Made it a very cheap way of getting about, and not any slower than taking the train or a coach. Reduced the average annoying slowdown to mere periods where suddenly everyone was going at the same speed as me Though I must say driving to keep the artic in front at a screen-filling but "safe" distance is a very odd affair... plus i discovered a way of telling when you're *in* the stream - engine temperature rises dramatically! (not surprising, given that suddenly you have maybe a 10mph airflow for a 3000rpm "idle")

In the states (USA) they do bumper stickers saying

"I'm not tailgating -I'm drafting"

- Its a NASCAR thing if you don't understand.....

Mind you they carry guns around with em in cars so road rage there is a completely different concept

[Tahrey1043]

LOL @ gareth..... ok to be as short as i possibly can

i was mostly thinking in terms of the 8p i tried to have put on.... the maths of the different situations are there ready-typed two of my posts previous the AHZ (?*) is same as a GT box insofar as i can remember. as for there being much "go" in 5th from 8p, frantic acceleration and high maximum speed is not really what the mod is about the engine has it's best go-ness - what there is of it with a 1043 - on the motorway in 4th, which is properly set for maximum speed at max power (or 3rd for good acceleration ie a brief stint in the middle lane getting past a truck in traffic) but is crap in general for cruising. And they're much the same box after all, 8p vs 4-speed.
(* im too lazy to check )

At truck-drafting speeds on 8P i'd be round max torque revs, supposedly good for economical cruising, and definately good for getting up the majority of hills without having to change down (I don't think i changed out of 4th for reasons other than stop/start for the entire journey, and that included getting round a drafting partner that hit a 1 in 10 (8? there was a sign...) hill and dropped thru 45mph before a biiiiig gap appeared..still on the same hill), and at 70 there'd still be a fair bit of reserve for easy cruising - sod what it says on PoloG40 site, there's no way this car's at 90% throttle at a steady 70... a steady *80* perhaps!
Most cars are geared lower than you think

The one with the slightly lower final drive would be an even better match for the 1L (~2800 @ 56, ~3000 @ 62) but like i'm ever going to track one of THOSE down

(whats that.... 20 lines?)
(opens bird cage to clear up worms )


NEXT SECTION

Yep that's a good economy equation - go brimful to brimful, take the distance travelled between pumps, divide by the litres filled, then multiply that figure (effectively miles per litre) by 4.54 (litres per gallon - accurate as you need or 4.5 if lazy) to get miles per gallon. Simpul.

So in your case 310/35 = 8.8 miles per litre (so it's less than 45mpg...) x 4.54 = 40.2..... pretty good for a 1.4 auto i must say! Though that IS at 55-60 so - erk!
Tips for saving fuel, um, not sure with an auto! I tend to change up as early as is comfortable and only down when i think it's going to labour, coast engine off when i can, etc. All of which are hard if not impossible with an automatic! The best you can really do with it is modulate what you do with the throttle - press it as gently as possible to get going to the speed you want and it should change up relatively early (though they're rarely programmed to do it anything below 3000rpm or to less than 2000) and if you need some more rapid acceleration without forcing it to change down...... try pressing the pedal to the floor slowly - you may find that the feel of the pedal changes at some point quite far down, like its going over a bump, hitting a switch etc... this is the "kickdown"/full-throttle switch that tells the gearbox you're hammering rather than just maintaining a fast cruise, and it's gonna change down, rev up, blow a lot of fuel etc. Try stopping short of that point when you can, the car will still accelerate fairly well but it wont drop cogs quite as much!

It kinda depends on how the gearing in your auto is set, too - the 4sp auto on dads Xantia basically has the same ratios as the 5-speed, but conversely to my polo one, it's missing first gear... so it's remarkably economical considering it's a 1989cc lump, even round town so long as you can get above 8mph (about it's idle speed!)

Not bothered much about what the truckers think - would usually be too close to show up on the mirrors so they dont even know i'm there, other drivers can go spin unless they start getting road ragey (i'll sacrifice some petrol in the sake of sanity)... its what the coppers might think i'm more worried about

[The Drummer]

Thanks for that. I thought that it was fairly good for an auto, but it does take it's toll sometimes, accelerating gently, never really going over 60 mph. Sometimes, I just want to put the ol' heavy boot down & give it some. But, being an Auto, it doesn't really want to know,

I don't mind too much though, I guess it's better to have the economy. Hoo hum....

[Tahrey1043]

plus it dont go nowhere quick when you do boot it

what is it, medical problems, hand-me-down, or just the only car you could get in a hurry? (dads is because of a knackered clutch knee)

[The Drummer]

Errrmmm, not sure really what possesed me to buy an auto. I think that the main reason was, was that it had only done 12,500 miles when I got it. It also has VW Alloys & flaps, apaprt from that I wish I hadn't.

I just have to live with it now. I'm torn between wanting to go like that clappers, the car being bone idle & not wanting to, so therefore punishing me by using lots of fuel, and wanting to have semi good mpg.

So do I a)bugger it, use the fuel you only live once b) save the fuel & planet?

[david burton]

or perhaps just hammer it when you like. get 35mpg and sod the extra tenner you've just burnt cos it's the best fun you can have for a tenner nowadays!


very impressive mpg guys, i'm never gonna get above 40mpg in my 16v - it's just too high revving - when i rev it

[KarlM]

So do I a)bugger it, use the fuel you only live once b) save the fuel & planet?

You buy something with one of the new Pump Deuse engines. Performance and economy (and the 1.4 is insurance group 3-5)