BMWs with small six-cylinder engines

[Pentoman]

PH opinion tends to be that all the six-cylinder BMWs (e.g. the 320i 2.2, the 325i 2.5 and the 330i 3.0) will do similar MPG, so you should just buy the bigger engined version every time. However I have been thinking that there may be a case for the smaller engined sixes such as the 170bhp 2.2 litre. My thinking is that you still get the great sound, and the smoothness, and you get acceptable performance. However the car should also be lighter than the bigger engined models. It should for example have lighter brakes and wheels (all important unsprung weight), lighter drive components (the gearbox and shafts and all that) and should be a slightly better handler as a result. Not to mention costing less to insure. So I think that appeals to me a lot - possibly more so than an extra 50bhp which you can rarely put to its full use. I'm also guessing they've got lower ratio gearing which is no great shakes in the UK, in fact I like that.
Thoughts?

[bolide]

If it was four-cylinder vs six-cylinder it'd be a no-brainer. But small-six vs bigger-six is a tougher choice

How do the kerb weights compare? I am inclined to think that the torque advantage will outweigh any weight savings

Nick Froome

[LocoBlade]

Sounds to me like someone looking for positives trying to convince themselves that the poverty spec model might be OK really!

I think some of your points are valid such as insurance, and if thats a big issue then thats a valid reason to consider the lower powered car, but regarding the handling and performance aspects even if the smaller engine had a few slightly lighter components, I seriously doubt you'll detect any improvement because of them.

[TonyRPH]

Having owned a 523i(E39) (2.5 6cyl), 323i(E46) (2.5 6cyl), and 330i(E46) (3.0 6cyl), I found that in every day driving, the 330i returned similar (usually slightly better) consumption to the 323/523.

I didn't get to drive the 330i on a long run, but my guess is it would have returned better consumption than the 323i.

Interestingly, there wasn't much difference between the 523i / 323i.

All of these were auto boxes btw.

[Romanymagic]

slightly off topic but also still kind of in the ball park of the topic; my brother and I had a rolling drag race a few years back, his car an E36 325 saloon and mine an E36 323 coupe, and he couldn't get ahead, as much as I could not overtake him, both cars were pretty much equally matched despite 20bhp between them.

[Robert060379]

My E36 320i (1991cc) costs £1895 less to insure than my brothers E36 328i would. Thing is the 328i is only a second and a half quicker to sixty, 20mph faster flat out and crosses the quarter mile 1.2 seconds sooner. My 320i does on average 12mpg more than his 328i and on the track the 320i has less understeer in oversteer out cornering issues. In my opinion the 320i is an all round better drivers car than the 328i dispite the 40bhp difference.

Edited by Robert060379 on Sunday 16th May 07:48

[Shropshiremike]

Robert060379 said:

My E36 320i (1991cc) costs £1895 less to insure than my brothers E36 328i would. .... on the track the 320i has less understeer in oversteer out cornering issues.

Surprises me that as a 328i should have a slightly lighter nose weight than a 320i.
The alloy block M52 is a lighter engine than an iron block M50. I guess you have different suspension set-ups

[Mustard]

The 2.2 (M54) 6 cylinder is a very very smooth engine BUT because of its smoothness and lack of torque if driven enthusiastically you are forever bouncing off the rev limiter and not making much progress, found then the earlier 2.0 M50 to be more usable (not tried a 2.0 M52)

Only ever driven one *23i (2.5) M52 and it drove like it was being strangled, *28i is much better

• 25i (M54) is much much nicer than the *23i M52 and runs an extra 20bhp (just over 190bhp)

My personal choice would be an M54 2.5 or 3.0ltrs (though high oil consumption can sometimes happen in the 3.0)

[4rephill]

Robert060379 said:

My E36 320i (1991cc) costs £1895 less to insure than my brothers E36 328i would. Thing is the 328i is only a second and a half quicker to sixty, 20mph faster flat out and crosses the quarter mile 1.2 seconds sooner. My 320i does on average 12mpg more than his 328i and on the track the 320i has less understeer in oversteer out cornering issues. In my opinion the 320i is an all round better drivers car than the 328i dispite the 40bhp difference.

Edited by Robert060379 on Sunday 16th May 07:48

not according to BMW, their official figures are:

BMW 320i:
POWER: 150BHP@ 5900rpm
torque: 140lb-ft
0-62MPH: 9.9secs
50-75MPH 9.7secs(in 4th)


BMW 328i:
POWER: 193BHP@5300rpm
torque: 210lb-ft
0-62MPH: 7.3secs
50-75MPH 7.6secs(in 4th)

(All information taken from owners handbook, based on manual gearbox)

So according to BMW, the 328i is 2.6 seconds quicker to 62MPH and 2.3 seconds quicker on in gear acceleration.

Whilst the 328i may only be 40BHP more powerful than the 320i, the far more important figure is the torque figure where the 328i has 70lb-ft more and this is what is required for acceleration, not BHP.

The 328i does weigh 20Kgs more than the 320i but it should also be realised that the 328i is artificially strangled back down to 193 BHP (via the intake manifold) by BMW for german tax reasons and that it's true BHP should be realistically @203~213BHP and therefore it's torque will also be higher and in the real world, torque is far more important when driving than bar room bragging BHP figures.(See here: http://www.e36manifoldconversion.com/home/m50manif... or search: BMW 328i M50 manifold conversion for more info).


As for BMW's with smaller six cylinder engines, it all depends on what you want from the car and how you're going to use it. If you're happy to cruise around slowly and don't drive particularily enthusiastically then the smaller sixes should be fine, but if you like to drive with a bit of vigour, you may well find that the smaller sixes leave you wishing you'd bought a bigger engine.

[Pentoman]

Alright... need to look into these weight figures and read some reviews. Clearly the big petrols have the extra acceleration, but for those who don't really need or want all that performance? I'm still wondering. The less torquey models should/could have a lighter gearchange/clutch, possibly things like more feelsome steering and smaller wheels/tyres and overall lower unsprung weight (?), plus the engines may be a bit smoother. If they have slightly lower grip limits that's no big deal, in fact possibly a good thing especially if they are approached with greater progression. Many reviews rate the handling of the lower powered/basic models of certain cars above the higher powered ones - they seem to prefer those with less weight over the nose and smaller wheels and tyres for pure handling. So, good though our modern BMWs are, they tend to be fairly weighty and are no nimble hot hatch on a narrow road, so I'm I still curious if a smaller six-cylinder could get closer to the best of both worlds.

[TonyRPH]

If you don't want outright performance, I would suggest a 325i.

Or if looking at a 5 series, 525i (E34) or 528i (E39).

The 323/523 are a bit strangled, as another poster has pointed out.

The E36's were also deliberately strangled, because of German horsepower laws (inlet manifold was restricted).

[Fox-]

Pentoman said:

PH opinion tends to be that all the six-cylinder BMWs (e.g. the 320i 2.2, the 325i 2.5 and the 330i 3.0) will do similar MPG, so you should just buy the bigger engined version every time. However I have been thinking that there may be a case for the smaller engined sixes such as the 170bhp 2.2 litre. My thinking is that you still get the great sound, and the smoothness, and you get acceptable performance. However the car should also be lighter than the bigger engined models. It should for example have lighter brakes and wheels (all important unsprung weight), lighter drive components (the gearbox and shafts and all that) and should be a slightly better handler as a result. Not to mention costing less to insure. So I think that appeals to me a lot - possibly more so than an extra 50bhp which you can rarely put to its full use.

I doubt it makes the blindest bit of difference. The only reason to get a 320i over a 330i would be if you can find one at a particularly good price. Otherwise it's not saving you any money in daily use over a 330i, and you might as well have that extra performance pretty much for free.

There is no real weight difference between the 320i, 325i and 330i. I suspect all the drivetrain components are the same anyway.

[Pablo16v]

Fox- said:

I doubt it makes the blindest bit of difference. The only reason to get a 320i over a 330i would be if you can find one at a particularly good price. Otherwise it's not saving you any money in daily use over a 330i, and you might as well have that extra performance pretty much for free.

That's a fair point. I would have preferred a 330i touring but ended up with a 325i because I couldn't find a manual 330i Sport Touring anywhere. My 325i had the right spec and history at the right price and was local so went for it.

[Tedswagon]

Might not be everyones cup of tea but I have the baby six in my E30. (engine M20 B25) and it is much smoother than any 4 pot I have driven before. MPG is the same in the M20B20 and M20B25!

[Robert060379]

While there is no denying the E36 328i is the better car on paper I could not see how the car is £1895 a year better than the E36 320i. In the end I just want to use the car on the track after the PPC £999 Challenge so my experience of driving both cars was aimed at that rather than a daily drive. If I wanted a Hovis car (best of both) I would have probably gone for the 328i as a motorway mile muncher and b road baiter but for what I was looking for the 320i ticked more boxes. As a platform to work up from there is a lot more to do to a 320i than a 328i and being on a budget as tight as £999 to build and race the car 328i upgrades and parts would cost a lot more than 320i ones.

[cheadle hulme]

Mustard said:

The 2.2 (M54) 6 cylinder is a very very smooth engine BUT because of its smoothness and lack of torque if driven enthusiastically you are forever bouncing off the rev limiter and not making much progress

Yup. I have this engine in my Z4 and its a lovely unit, but not torquey at all. Really needs revs to make progress and as said, easily bounces off the rev limiter if you're ham fisted in gears 1~3.

[ZeroSum]

Don't forget that BMW changes the differential ratio with engine size. The 330 has a longer ratio than the 325 or 320 hence similar or better fuel consumption.

There is negligible weight difference between models perhaps 20 or 30 kg.

[LocoBlade]

Robert060379 said:

While there is no denying the E36 328i is the better car on paper I could not see how the car is £1895 a year better than the E36 320i.

What's best for you and what's best for the majority are two seperate things, as the £1900 insurance premium on a 328 is something that's only relevant to you. It certainly makes the 320 a no brainer for you simply because the 328 is too expensive for you to insure, but for most people over 25-30 the difference between insuring a 320 and a 328 wouldn't be anywhere near £1900, in fact both could be insured fully comp for well under £300 in many cases so that differentiator is almost irrelevant.

[Yelly]

Romanymagic said:

slightly off topic but also still kind of in the ball park of the topic; my brother and I had a rolling drag race a few years back, his car an E36 325 saloon and mine an E36 323 coupe, and he couldn't get ahead, as much as I could not overtake him, both cars were pretty much equally matched despite 20bhp between them.

According to BMW, there is 20bhp between them, but I don't believe that for a second. They are very, very similar.

[Matt UK]

I had an e46 320i. 6 cyl noise, mpg and running costs yet 4 cyl performance.