Uh oh - 'what car' car opinions sought - BMWs

Depends what you mean by 'a run'. On a motorway I have to cruise at 95 to get my 528 under 30. And it's an auto. Normal motorway consumption is

32-33. At normal BMW cruising speed. ;-)

London rush hour traffic about 16.

My E30 is an auto. Seems to do about 30-32 when cruising on the motorway.

In usual city mooching about mine does around 18-20. Never seems to be worse than 18 mpg, but I have to nurse it to get more than 20 in town.

Having said that, if I nurse the Rangie in town I'm lucky to see more than 12 mpg at the moment, but never much less. Weird the way that happens, if I nail the thing everywhere it does 12ish, tickling it doesn't seem to save much fuel. I did once manage to get 22 mpg from it on the motorway.

i've obviously got a lighter foot than you guys, i never drop below 25mpg even with a bit of traffic

I managed to get 54mpg out of the 406 on a run the other day. I really did pootle along at 60, but there's no fun to going fast in that car. You don't know you're doing it in the same way as you do in a sportier car, you get there a bit sooner, and your expenses don't stretch as far.

Pay no attention to SteveH, who if you were nicked speeding, would be the first in the queue of four cylinder willy waving at you.

For what it's worth, my turbopetrol Saab has averaged 39 since picking it up...

The official figures for my car are like, 10mpg more than real life hehe! The best I've ever seen reported is 35mpg, on a long run, at like 45-50mph in traffic heh. I've never got over 26 average from a tank, except when I've been on long runs (the Europe trip for example) it'll do 31/32 it even showed 33 for a bit, if you're cruising at 70-80, taking it gentle. But it was at 30.9 maybe 31, I can't remember, when we set off for home from Monaco, and that was 27 by the time we got home. As we had 1300 miles to cover, I didn't spare the the throttle. We cruised at 95-100mph all the way up through France, passed a few cameras hehe, that were naughtyily marked on my satnav, but f*ck that, if the Gendarnes (sp?) were gonna try pulling me I was gonna run for the border ;-)

...maybe.

:-)

Heh! Don't forget that my commute is mostly flattering for the car. It's too busy for me to bother trying the outside lane dance. On the A162 there are often a few coppers about and besides, I'm going to *shudder* Pontefract most of the time; nobody should be in a hurry to get there... I always

*always* get better mileage driving back to York.

Driven with the cruise set at 70 all day, it shows around and about 38 to

1. That's what I get during the commute too. In the city, yeuch, poor mileage - but we don't drive in the city, we bus, cycle or walk it (as it's quicker).

I am working on driving to Paris Euro Disney gubbins as Charlie takes the train.

That's because the part-throttle maps aren't optimised and closed throttle is overrich. Acceleration curve are 3 to 4 times the normal fuel rate. "Old" ECU's developed before the wide band-Lambda sensor all have that thing.

The Emerarld ECU and our 928-ecu has a self-lerarning mode: you drive around and the computer is all the time checking the exhaust-gases )pre cat)and regulating the fuel-to-air-ratio. On the Emarld everything is stored in the ECU-memory, on the 928 (older version) I have to burn an Eprom.

On the 928 I have a laptop on which the screen is filled with red boxes. each box represents 200 RPM and the are 20 rows indication throttlepostion from close to WOT. In each box is the duty cycle of the injectors indicated.

When you drive around a box lights up and you see the dutycycle change. On the optimum it becomes green. The fuel computer indicates at the same time the drop in fuel flow.

For the 928 I have the fuelmaps now on all throttle setting up to 65% power. Remarkable is that the bugger uses less fuel at 180 Khp than at

90 kph... Secondly the map above 240 is not optimised and uses the OEM Porsche settings multiplied by a coefficient to account for the bigger engine: fuee flow goes through the roof then. I am begging for a high speed oval (on which I can steady the fuel rate) in order to reprogram.

Long story in short: LAmbda-sensor for cat are narrow-band, it's like on/off and the ECU takes close to no info from it. The wide range Lambda-probes allow the ecu to optimise combustion all the time.

The new Emerarald ECU goes even further: it contains 3 indepents maps. You can choose "max power", "best economy" even program a map if you want to drive on regular fuel in stead of super. It's great for modified engines. I don't know for the Range Rover but for some Rover engines you can get a pin-compatibe Emerald brain. It ain't cheap though.

Tom De Moor

You're gonna do a TG style race :-D?

must be something wrong, I only got 26mpg out of any saab, turbo or not. Old ones though...

is that motorway?

We couldn't possibly call it a race as that would invalidate the insurance... :-p

Depends. One commute yields better mileage but is boring (30 miles, 27 motorway). I usually take the shorter route, 27 miles (6 motorway, the rest are A or B roads).

Jeez. A race between Dervy and a train.

Actually, yeah. Do it, man.

Lambda sensors? On my Range Rover? Um. No, there aren't any of those.

It's also running two ECUs. The original Lucas job and a custom made Zytec system that runs another map for the turbo and it's associated gubbins.

Having said that, last time I had it hooked up to an emissions analyser it was running remarkably sweetly, but wasn't under load.

For the new adaptif ECU's a plug is welded on the first part of the exhaustcolletcor (as near to the engine as possible and before the catalysator). It will receive the wide band Lambda-probe.

At best your modified ECU is configurated on a rolling road during a 2 to 4 hours-session. The operator first checks if the car runs and starts fine (when cold/warm) and then tries to get a cood combustion and dito power on the rev-range. The part where the turbo gives no boost will be the same as the orignal engine-settings.

That implies also that your map is static and will not adapt to new situations, use, aging, different fuels etc. Keeping in mind the very low number of turbo'od Range Rovers it is highly unlikely that the modified map is rather complex or that programming on lesser loads is done (most rolling roads don't have 4x4 capacity and they definitely don't like big power turb'od engines for long durations under load). Half load fuel flow will be half of WOT fuel rate, and so on.

A fuel map in a mass production car takes about 1500 Hr of testing to complete, again low volume cars tend to have less optimised maps in order to avoid that cost and because after all the owners of those car are less bothered by fuel consumption.

Without load, the turbo is not activated, your engine is basically standard and the emissions are those linked to the idling settings set by the constructor of the engine.

I have to say that the new "self-learning" ECU's are quite impressif and it is surprising that manufacturers haven't jumped on the wagon yett. Their orginal mapping is considered to be good for all engines regardless of tolerances. This is fine but it leaves 5-10% power sleeping in the engine and -on the worst cases - 20-25% in fuel consumption.

On new cars these less-than-optimum-maps doesn't show up on exhaust gas analysers as the cats reduces CO-values and unburned gases to zero.

The self-learning ECU finally give feedback about the quality of combustion whereas is the stone ages we just changed a calibrated orifice in the carb and hoped for the best.

In the middle ages some of us got their dirty hands on programmable ECU's and computers. That was a mayor step (our hands got clean in the progress ;-) ) but still the map was depending on extensif testing and only correct on the time of setting up.

Finally we are here and today: the new ECU start from a basic map and modifie themselves, leaving the time to go to the pub! We don't drink a lot though: as with all new toys these Ecu's tend to be expensif.

Tom De Moor

[snip]

Ought to be interesting in a boring way... ;-)

Leave home at say 07:00 hours, Charlie must use public transport, I get to use the Saab's navigation. She isn't up for it and claims she'd win easily as I won't break the speed limit.

What sort of top speed are we talking?

And what sort of bhp, and 0-60 etc? I know we're hardly comparing an SL55 AMG to some sort of quick Ferrari, but I'm just wondering how it'd compare to my Sprinter in terms of as-high-as-possible speed runs.

Problem is, the Sprinter's got a weeny 4-pot engine. Must order the new shape one with the 258bhp V6 one, and a big enough gas tank so that range isn't an annoying issue....

My gas ECU is self learning. Constantly sniffing the emissions via the lambda sensor - I know this becuase I wired in the lambda connections myself, just like everything else :-)

It is a great system where you tune a car just by taking it for a drive.

For the Exploder it's 121 mph on the GPS on the flat, 210bhp and 0-60 in

9.6s.

Mine's supposed to be slightly faster all round than the standard one, but I'll be f'ed if I can see much difference.