28i and 30i MPG in real world driving

[JakeS76]

The official mpg of the 28i is identical to the 20i according to BMW. I got around 35mpg in my 20i. So would moving to a 28i be similar or should I expect it to be a lot less?
And I assume the 30i six pot is significantly lower mpg but sounds better? If anyone could enlighten me that would be appreciated.

 

[Mr Tidy]

I haven't had an E89, but I've had two 3 Series and two E86s with the same N52 engine as the 30i.

I had stopped working before I had any of them, so no commute and I could avoid rush hours, but used that way they averaged between 32 and 34mpg.

A 28i ought to be much the same as a 20i I would have thought, unless you keep using the extra grunt!

 

[B21]

Folks tend to move quicker with more power..so unless you drive to a prescribed speed etc the 28i will burn more fuel than a 20i..the 30i will be slightly more economical..based on many many miles with N20 and N52s together on the same route etc

 

[Pondrew]

The official mpg of the 28i is identical to the 20i according to BMW.

As you say, the official mpg figures are identical for the 20i, the 28i (and the 18i actually). I was always under the impression that is because the 28i is the most efficient of the three flavours of N20 factory maps. So the 18i and the 20i 'waste' some of their fuel as the boost maps peg the air pressure back.

Having owned a remapped 18i (to 280bhp and 350nm) and a standard 180bhp 20i, both used on the same journeys most of the time, I can report that the fuel consumption is identical on both (around 35mpg average). When the 18i was factory-standard at 156bhp, it was no better on fuel TBH, hence my theory of 'wasting' fuel on the lower power variants.

No idea about the N52, but many have experience of them on here.

 

[JakeS76]

The mpg sounds ok for me. Is the N20 or the N52 more reliable? The N20 has timing chain issues but is the turbo an issue? I had a look on the forum but couldn't find much specific for the N52.

 

[B21]

The mpg sounds ok for me. Is the N20 or the N52 more reliable? The N20 has timing chain issues but is the turbo an issue? I had a look on the forum but couldn't find much specific for the N52.

The N20 turbos never presented any real problem..cam chain is a pre 2015 issue…although the N52 when new was more reliable than the N20 when new most N52s are now a bit older..so relatively simple issues like water pump failures and multiple gasket , cracked plastics are more frequent…IMHO..

 

[Mr Tidy]

N52s seem to be pretty bulletproof - I've seen a couple of threads on here recently about N52s with 180K and 230K miles.

It's the ancillaries that tend to fail, like alternators, starters and the notorious electric water pump. I've had one water pump die at 60K, another at 135K so although it's inconvenient and not cheap it's probably only going to happen once in most peoples' ownership.

My current N52 in my 2005 330i has needed a new cam-cover gasket and oil filter housing gasket because over time they get brittle so they leak. But a 30i will be at least 4 years newer so might not have those issues yet.

I've no experience of the N20 engine, but a new cam-chain sounds more expensive than new gaskets.

The N52 will have a better soundtrack!