I thought about doing this, however to remove the timing cover you have to remove the oil pan which means dropping the subframe. They don't make it easy doing on the driveway/road.Do you have the M57 engine? if so I believe it's around £670 including 1 years warranty as the chain is at the front of the engine. If I'm not mistaken the chain should be changed around 100k but I honestly can't remember where I heard that and I'd agree frequent oil changes would help pro-long the life of the chain but as you probably know they can just go, or if you're lucky it will stretch first making it rattle which is your life saver. Personally, I'd put it on your list of to do jobs, assuming you look after the engine with regular oil changes a chain swap at 140/150k should see you to 300k assuming you keep it that long lol.
A quick Google searched returned some like this and more:i have an e46 m57 tu engine,,on 153 k miles,,and ive never heard of one chain snapping/stretching..im sure its probably happened as nothing is infallible...my e90 is on 122 k miles and i do not intend to do the chain and im probably keeping till its dead,,its had frequent oil changes as has my e46..but if it aint broke,,in this case id leave it...how many chains have snapped? and how many on m57 compared to n57
Referring to your thread, your car has the 2L n47 engine which is prone to snapping chains, the completely different older generation m47/57 engined cars don't suffer from this problem. As others have said above, any issues will almost certainly be because of a lack of oil changesHi m8 I had 130k on clock and chain broke on motorway so the aa reckons. had it towed to house where its been for three months. couldn't start engine, battery went completely dead now struggling to get battery out to charge. nightmare.