Cool run - fuel consupmtion comparison

[Jazzbass 1]

Last week I caught up with an old mate who has an e39 523 manual, same year as my 528 auto. We went for a run together to Taupo and back (from Palmy).

The fuel consumptions figures were interesting:

523 12.2 l/100kph

528 8.7 l/100kph

Well, I thought it was interesting, anyway. He was less impressed.

The last time I can recall doing a comparison was in 1973 when a mate & I had - wait for it - Austin Kimberleys - his was manual, mine auto. We went on holiday together and the manual ran at 23mpg with the auto at 27mpg.

We should all depend upon our own experiences, rather than believe what other's say, so for me - based on my own experiences - a manual car is less fuel efficient than an auto in the same conditions. I know - 4 cars is hardly an effective sample, but there ya go.

[bumpstop325 0]

How close were you following?

Did both of you use cruise control? Using this makes a huge difference in usage.

[Carl 3]

Driving style, diff ratios, gas type, tyre pressures, car load, drafting...

[Jazzbass 1]

Yes they all make a difference. Neither of us have cruise control, each car had only the driver in and we swapped the lead - a lot

However, I am a smoother driver than him, I guess I'm a throttle squeezer rather than a stabber and I think that could be a part of the difference. We both use 98 so there was no difference there.

Like I say, its all pretty meaningless, but we had fun and I have a hold (however tenuous) over his gas guzzler now!!

[mops 4]

yep, manual with smaller engine will have shorted dffr ratio and that will greatly contribute to the fuel consumption. I would be interested to know, if both of you are driving say next to each other at, say 110kph, what kind of rpm's are you at ? I bet 528 auto will be nearly half of 523 manual... and that affects open road effiecency greatly...

on open road driving stule doesn really affect fuel consumption much (you sais you were going pretty much together) - unless you are racing with heavy breaking every corner and stuff for extended periods of time...

maybe his car is running rich due to, say bad pplugs or clogged oxygen sensor or something along those liunes.

[kiwi535 538]

mostly down to the driver,even with identical cars you may have found the same difference ie 12 vs 9.Not many people claim autos are more efficient!