Impact on fuel consumption of an auto box on a 320d

[Mr_Sukebe]

From checking Parkers, the manufacturers fuel consumption figures for the 320d manual and auto are 49 and 42mpg respectively.
Assuming the relationship is fairly reasonable on those figures, where do people think that the auto is mainly burning more fuel, is it on the longer motorway runs, or in town? I got the impression that the newer auto boxes have "lock up" when cruising, which would infer that there should be very little between the two cars on long journeys.

Any thoughts?

[gizlaroc]

Pre sept 2007 Efficient dynamics there was a lot more in it than the figures suggest.

I have had three 2.0d autos from BMW, the E46 which returned 33mpg (38mpg at best on a steady run) and the 120d 163bhp auto which returned.........33mpg and again 38mpg at best on a very steady run.

The third was an ED 320d auto m-sport tourer, it would return 39.7 pretty much all the time, and on a run you could see 45ish.
39.7 was an average, I do 30k miles a year, just short stop/start journeys would be sub 35mpg, don't think a manual would drop that low.

The manual I borrowed would get 44 and 57 respectively.

I think the difference with the newer cars is they are getting better round town.

Oh, and I borrowed a 330i petrol too, ED 272bhp version and that returned 38mpg over 2 days and nearly 500 miles, so I was a bit disappointed with the 39mpg from my 2.0 diesel to be honest, the petrol was a far, far better proposal and the way things are now would actually be cheaper to run.

[Mr_Sukebe]

Was the 330i a manual? I have a 330i auto and get at best around 30mpg on a run, and around 20-25 in and around town.

[Job38]

If you want economy then avoid an auto.
(come to think of it, if you want fun, avoid an auto )

The irony is, in the age of the 'performance diesel' only auto boxes can handle the torque economically.

[carlovers]

ive got a 120d auto 177bhp ED With a tuning box.On a 100 mile run up the M4 ,which included some fun and i DO mean FUNwith a mitsubishi evo.Believe it or not(as someone famous said recently YES WE CAN (it done me but incredibly not a lot in it and believe me he was trying)Anyway digressing bearing that in mind averaged 43.On a more sedate run would get around 47-48.

However recently did 9 miles around outer london postcodes w4 w3 nw10 late morning normal traffic and achieved the wonderful figure of 21mpgApparently diesels dont like stop start stuff ,never warm up properly,not forgetting my auto has no stop/start tech.Oh and gizlaroc my navigon is still performing magnificently

Edited by carlovers on Tuesday 11th November 14:28

Edited by carlovers on Tuesday 11th November 14:29

;)

Edited by carlovers on Tuesday 11th November 14:30