[Ant Man]

My next car will be the F25 X3, either 30d or 35d, depending on which feels most like a NA petrol.

Comparing similar model years, can anyone offer some personal experience on which has the most spontaneous throttle response and the least turbo lag?

Cheers
Anthony

[dopper99]

I think the whole point of the 35d engine was to solve to two issues you have mentioned. Having two turbos virtually eliminates lag and gives increases thottle response, as far as I can tell. However, this does make for a linear power delivery so you lose the surge like you get with a single turbo.

Depends what you want, for me I find a linear power delivery less exciting and much prefer the usual diesel turbo kick-up-the-ass you get with most single turbo diesels.

The only time I find my car to be "laggy" is when I'm in the wrong gear. For example if I'm lazy and stay in 3rd whilst dropping the revs below 1000rpm (I have a 6sp manual BTW), then applying the throttle it obviouly doesnt do a lot for a few seconds - but this is my own fault for not being in the right gear. I guess an auto wouldnt have this problem and would change down to the correct gear. But apart from that I wouldnt say my car is laggy.

[SteveC]

Originally Posted by Ant Man

My next car will be the F25 X3, either 30d or 35d, depending on which feels most like a NA petrol.

Comparing similar model years, can anyone offer some personal experience on which has the most spontaneous throttle response and the least turbo lag?

Cheers
Anthony

Most of what people think of as turbo lag is more accurately attributable to the auto transmission. In normal 'D' mode if you floor the gas from standstill or even when rolling, the AT pauses before kickdown and the response is quite slow, as if its waiting for the turbo to spool up. Put it into 'S'port mode however and that delay is all but gone, with the car leaping off the line in response to a 'futload' of throttle.

The '35d uses 2 sequential turbos while the '30d uses a single turbo with variable vane technology, which varies the turbo geometry according to revs. In the MT version a 330d has negligable lag. In 'S'port mode the 35d is also pretty nippy.

So in summary, turbo lag is really a non-issue these days and in AT models, throttle response is dependent on whether you select 'D' or 'S' mode.

[davyk31]

35d for me, power on tap all the time and no waiting for a big surge. Haven't yet tried the engine with the 8 speed box, must be brill.

[AdrianSi]

My father has an 09 plate X3 (E83) 35d with the M57 engine and I have an E90 330d LCi (manual) with the N57 engine. So the X3 has the older twin turbo unit and I have the newer engine with the variable vane turbo In my 330d. The F25 models all use the N57 engine.

First off is say that the twin turbo unit in my fathers X3 is smoother than my 330d and mind just sounds a little harsher. This may be the same on the twin turbo newer engine which I haven't heard. Just from idle, if you rev the X3 it feels more responsive, free'er and more eager as you'd expect having the additional smaller turbo. With the newer engine in the F25 I imagine this will be the same.

That said tho, my 330d has a very linear throttle response and you'd be hard pushed to know that it is turbo'd as there is no distinct power surge from the turbo. With the manual gearbox you can drive around everywhere at below 2000rpm without the engine even hinting at labouring. It's a more effective use of power than having to allow the turbo to spool up and be given in a single burst.

My fathers X3 tends to average at around 28mpg around town, 35mpg on a good run. The auto box seems to hold the gears for quite a long time but no idea how this fairs with the F25. I think even if you went for the 30d you wouldn't be dissapointed. Be interested to hear of the differences between the 30d and 35d.

[Ant Man]

Appreciate the comments guys.

Does anyone have any personal experience from driving both engines from the same age?

Interestingly a German magazine tested both the F25 30d and 35d and from the results would indicate that the 30d has the better throttle response which I found very interesting. Given the 35d has two turbos, I was expecting the reverse. Which turbo spools up 1st? The small or large?

How responsive is the turbo and throttle when keeping to one gear?

[creepy coupe]

Any model with the 8 speed auto box and you will never be in the wrong gear and off boost. I found the 35d sounded a bit rough in the X5 and X6 I tested. Might have been the weight of the car making them work hard.