Aghast at MPG...

Philip Chidlow · Post by **Philip Chidlow** » Mon Feb 20, 2006 10:27 am

Well, I did a 470 mile round trip this weekend in my 153K GTI auto, most was tonking along at 70-90 on the motorways (including a doing a bit of vehicle testing on the M54 - á la traffic cop - that saw about 118 on the dial) but did include plenty of cross country dashing about and about half an hour crawling along at 5-10 mph on the M11 last night... And my fuel consumption (99 Octane Tesco's finest) - and I have double checked - was a quite unprecidented 30.1 mpg. That's pushing 6 mpg better than my best so far.

Why? The car's been recently serviced, but...

I've been thinking, even if I had a litre more on the filler neck than I put back in, that doesn't make much difference. I am more impressed by BX than ever...

(And before you diesel boys start getting all smug, that mpg is still good by many of today's standards!)

Way2go · Post by **Way2go** » Mon Feb 20, 2006 11:57 am

Yes, that seems similar to my GTi auto. I normally average 29 mpg for mixed motoring but it will drop if I do a lot of slow stuff. Long distance mainly motorway can give 35 ish.

What kills the mpg figure is on normal roads unlike manual cars is it's almost impossibe to stay in high gear. 4th will engage at 42 mph and drop back out at 38 which is infuriating when driving on 40 limit roads. (Got to be "good" now cos we have a plague of speed cameras round here and even some naughty ones on the M4)

Is there a reason that you are using Super Unleaded? I have great power & performance on standard 95.

Philip Chidlow · Post by **Philip Chidlow** » Mon Feb 20, 2006 12:18 pm

I put higher octane fuel to see if it made a difference... that's all. There seems to be a slight improvement in response, and it would appear, in economy. Whether or not it justifies the small increase in fuel cost is debatable.

I would have thought 35mpg is do-able on a motorway cruise, at a steady speed for much of the way... For me though, where I do a 9 mile round trip in it twice everyday - as I've said on a previous thread - I have been lucky to get 21mpg. The engine's probably a little worn so I guess that won't help.

My other GTI auto (still with 109K on it) does better by as much as 3 mpg. Engine rebuild at 80K must have helped.

I agree about the 40mph gear ratio - a bit of a pain - but it's unlikely that a camera will snap you at say, 43mph in a 40 zone... Or will it?

Way2go · Post by **Way2go** » Mon Feb 20, 2006 12:58 pm

Just checked last figures for last tank and that would be 26 mpg. I've got a neat little program on the Psion that you can enter figures in metric, Imperial or mixed to give you the answer. So distance in miles, fuel in litres, return = mpg.

I generally reckon to getting 300 miles from a tank full without running on the amber light. The best I've ever done is probably 400 miles on a straight drive to Scotland.

With regard to the speed cameras, I wouldn't count on it as I've heard that the tolerance has been wound down now, particularly on the 30 limit cameras. After all, these cameras now have more to do with revenue generation than deterrance. I don't think that the the old story of giving you a 10% speedo error allowance happens or is something you can argue!

43 mph is perilously close to +10% so would need cruise control to maintain it without going over. Cruise would further help cos you could set to a legal 40 and just give a "blip" to engage 4th.

That irritating driver ahead that is slower than 40 is still where the plan falls apart however.................

Philip Chidlow · Post by **Philip Chidlow** » Mon Feb 20, 2006 1:17 pm

Hi your reply prompted a thought - how much fuel is in the tank once the amber light comes on - I always reckon on about 16 litres or 3 1/2 gallons... meaning a range on 'reserve' of a maximum realistic 75 miles... Am I being optimistic?

jeremy · Post by **jeremy** » Mon Feb 20, 2006 1:49 pm

I never trust the lights and so measured roughly how much was left by filling the tank just after the light came on. My car is a BX TD Estate with the additional small tank which means it should hold 14.4 gallons. My calculations are that there is about 1.5 gallons left - but I still don't trust it as I've never measured the tank capacity from empty and so am relying on tha manufacturers data. The other reason is that with the back of the car dropping when stationary and the additional tank I do wonder how likely it is that the pick up will come out of the fuel allowing air in. the same could happen on a hill.

I think the ZX one comes on at about 9.5 gallons out of 12 gallons - I'm sure it used to be about 8 - when the gauge hit the red zone. That seems to have moved over the last 3 years - must be a mildly defective sender unit.

jeremy

stuart_hedges · Post by **stuart_hedges** » Mon Feb 20, 2006 2:06 pm

No smugness here, Philip, 30mpg is very impressive. I pay for my diesel's 45mpg with extreme slowness!

Like yourself, I've found Super to make a difference to the older petrol-driven cars I've had. The GSA's definitely preferred it and it made a difference to the 309 too. Newer cars - such as my mum's 1995 Pug 106 - don't seem to be so fussy.

Way2go · Post by **Way2go** » Mon Feb 20, 2006 2:58 pm

Philip chidlow wrote:Hi your reply prompted a thought - how much fuel is in the tank once the amber light comes on - I always reckon on about 16 litres or 3 1/2 gallons... meaning a range on 'reserve' of a maximum realistic 75 miles... Am I being optimistic?

Hi Philip, this may be optimistic

Yesterday I filled when the needle was touching the beginning of the red to the second click of the pump which recorded 53.53 litres. So if you subtract this from the 14.5 gallons of tank capacity there should have been about 2.5 gallons left and I was probably about 0.5 gall or so from illuminating the light.

The above confirms what I previously thought, that it was about 2 gallons at the light giving 30 miles comfortably to get to a petrol station & then nervousness if you don't.

saint gaz · Post by **saint gaz** » Mon Feb 20, 2006 3:48 pm

On my bx 14 tge the best results i had on a trip was the first day of the "fule crisis" 3-4 years ago. On leaving London i filled up. Then as News was filtering through about stations closer to home (merseyside) running dry i again filled up at sandbach services. Did a calculation and worked out approx 52 m.p.g. At the moment i tend to get round about 34 m.p.g for "town" stuff. And on a good trip 38 ish for m/way. Not to bad when you consider that most of my motorway stuff would be over the pennines.
As a general rule my citroen mechanic advised me that once the red light becomes fully iluminated on a trip you have around 30 - 40 miles to find fule.

Way2go · Post by **Way2go** » Mon Feb 20, 2006 4:59 pm

saint gaz wrote:On my bx 14 tge the best results ...... approx 52 m.p.g. At the moment i tend to get round about 34 m.p.g for "town" stuff. And on a good trip 38 ish for m/way.

Hi gaz, yes us with the GTi's pay a high premium for performance until the gap gets narrowed on the motorways.

But strewth 52 mpg

, that was good and puts you up in the economy league of the diesel boys.

Ian_Fearn · Post by **Ian_Fearn** » Mon Feb 20, 2006 6:03 pm

My old GTi hurricane would easily achieve 30mpg on my normal everyday running and as much as 40 once on a constant 50-60mph run to Lincoln.

The 4x4 is good on the motorway at 70mph ish, obtaining around low 30's. Round town its pretty hopeless, i normally expect to get low 20's and maybe around 23-26 for an average.

I still maintain that the 8v GTi is the best BX ever. Loads of grunt with good mpg to boot.

I'm sure a raft of people will tell me the 17 Turbo is only slightly slower with more mpg but for me diesel doesnt have the right sound!

ken newbold · Post by **ken newbold** » Mon Feb 20, 2006 6:08 pm

Sorry Ian, but I just love the sound of the filling station pump clicking off knowing that I've got loads of MPG.

Philip Chidlow · Post by **Philip Chidlow** » Mon Feb 20, 2006 6:15 pm

Well, I don't know what's happened, but I just topped the tank off again and it would seem from the amount it took to fill to the brim, I am now comfortably achieving 31.5 mpg. I haven't done anything so whatever was causing a poor mpg before is gone for now. I wonder if the new air filter is to thank!

Way2go · Post by **Way2go** » Mon Feb 20, 2006 6:36 pm

Ian_Fearn wrote:My old GTi hurricane would easily achieve 30mpg on my normal everyday running and as much as 40 once on a constant 50-60mph run to Lincoln.

Seems excellent Ian, maybe the difference is the ECU (Jetronic) as my E & F reg GTi manuals gave better mpg than this J reg with the more advanced Motronic system. I had put the difference down to being an automatic.

Philip, I have been reflecting in general on whether to change the air filter. Based on your result it's moved to the top of the priority list!

Mike E (uk) · Post by **Mike E (uk)** » Tue Feb 21, 2006 10:36 pm

I have had 42mpg from my 16V on a couple of long trips. Over 500 miles on a tank.

That surprised me enormously. I don't dawdle along either.

the car has the taller 5th gear mod, which would work very well on any GTI.

I want to try the 100ron fuel, but not seen it around Bucks.

Apparently, it is fossil 95 plus alcohol, so it is environmentally more friendly!

If it gives me more power,I will certainly consider the 'greener alternative'

Mike