Is the N54 really that bad? I was looking at buying a convertible for the summer. (For the kids - honest!)
No, the N54 is a master piece, and it seems that a lot of it's overwhelming positive points are overshadowed by slight negative points.
The only thing that scares me with my 335i is the turbo's going, because that is a £2-2.5k job and there is no getting away from that.
HPFP/injectors etc - don't bother me anymore. Part prices have dropped massively in the last 5 years and now an amateur home DIYer can do a lot, as long as they have a laptop handy, the right software and the ability to follow online DIY posts.
I will not be renewing my warranty this year as the price of it is continually going up (even though i'm still under 60k) and this coupled with the fact that the part prices have dropped and that any good BMW independent can do almost all jobs, means that, for me, it isn't worth it anymore. There was as time, when the E90/E92 was new, that only BMW could do coding etc to the car and had all the toys, and things like injectors were £200 each. Now, as i said, all good BMW independents can do most jobs and injectors are now around £111 each.
The only other thing i should make you aware of with regards to the warranty - it is absolutely fantastic if a part which is covered fails completely. However, with a lot of car problems, this does not happen. Often there are intermittent problems, which often the car won't commit to it's memory, so when they plug it in, there is nothing in the cars error memory. This is very frustrating as they will refuse to do anything unless they can get a fault reading. This is excluding those problems where the car simply just doesn't feel right, but there are no error messages per se. If you have one of those, like your gearbox is not changing smoothly - forget it. In these instances, you may as well use your warranty as toilet paper for the good it'll do. What will happen is you will have to book the car in for an entire day (and you'll possibly have take the day off to do this), one of their "highly trained mechanics" will drive the car, you'll pick the car up at the end of the day and they'll tell you "Our mechanic couldn't detect anything wrong with the car - thanks for stopping by. Have a nice day". Unless there is a fault code - dealers simply don't want to know these days. Dealers don't employ mechanics anymore, who investigate problems and try to find solutions, they employ fitters who also happen to be able to plug a car into a computer and if computer says no, that's the end of it - as far as they're concerned - the car is fine. And it is for this reason i will never take my car to a mechanic for any sort of repairs.
In fact, i've currently got the full comprehensive BMW warranty and got a fault light coming on every now and then, and i'm reasonably sure i know what it is (VANOS - £70 for a new one x2). However, i still can't be bothered to take my car to the dealer to have it fixed because i know what will happen - i will waste my entire day taking it 20 miles to the dealer, they'll plug it in and say "sorry sir, there is no fault codes in the memory. Let us know if it comes back on. Thanks, bye."