Bmw M235i @ M240i Difference?

[Trevor555]

I'm going along with a friend to look at/buy one tomorrow, a M235i 2015/65 plate.

Is the M240i just a rebadge with a bit more power?

Or is it worth getting the M240i?

[jaa1aut]

Having specifically sought out a 235 rather than a 240, the difference is the former uses the older N55 engine, rather than the latters B58 modular engine. I wanted the more proven older engine as I'm planning on keeping it a long time, at the expense of more power & fuel economy.

[GregK2]

I would go 240. The B58 is the better engine in every way except maybe sound (Subjective)

[jaa1aut]

@GregK2 apart from VANOS (and associate cam chain) & oil filter are at the back of the engine, making it a pain to service.

[HM-2]

I tested both when I bought my M140i.

Overall the B58 (40i) is the better engine. It loses a bit of top-end fizz but it's better everywhere else in the rev range with better economy and a markedly better throttle response, though how much of that is software I don't know. Sound has already been mentioned, it's subjective but most seem to prefer the N55. I'm neither here nor there.

It should, in theory at least, be the tougher engine long-term- it's a closed deck block. There don't seem to have been too many reports of issues with them even in track use- the N55 is generally very good but some people have experienced oil starvation issues on-track (which usually means new engine). There are fixes for this using aftermarket parts and possibly also M3/M4 bits, I can't remember.

If you're modifying, the N55 is currently better for a couple of reasons; longer lifecycle being the primary one, but also the fact the ECU was cracked a longer time ago (hence more people being able to live map them) and the use of an air/air intercooler rather than water/air, which makes chopping and changing significantly easier. That said, B58s have made over 500whp with just bolt-ons and a larger turbo so it's hardly "bad" in that respect


I think the 40i cars have revised suspension geometry over the 35i ones, though that might just be the 1, not the 2.

[Driver101]

The M235i revs, sounds and feels better to drive. The M240i has better low and mid range grunt. It is slight faster. It's about 0.5 second faster to 100mph.

The M240i is slightly better on fuel and has cheaper road tax.

Options, price and condition would influence me more than the engine.

[Trevor555]

Thanks for the great replies.

I'll suggest to him that he should look at both and make his own mind up.

They do look good value at 20k ish.