I got my introduction to BMWs when my Dad told me he was looking to sell his 2004 525i e60 with 160k miles on it and asked me if I would be interested in buying it, which I did. While the 2.5l i6 isn't a powerhouse, I was impressed with BMW's driving experience.
I owned the e60 for nearly the entire RX7 build and daily drove it to ~230k without any major problems and only regular maintenance items to worry about. When I sold the RX7, the e60 also went on the block for consolidation purposes, but I would be lying if I said I didn't miss it and wish I hadn't.
In 2015 after selling the RX7 & 525i I switched sides and tried a 04 Mercedes E55 AMG. While the 500+ HP E55 hits insanely fast for such a large sedan, I never really felt connected with the car. The E55 had a LOT of bells and whistles. I thought that would be a good thing, but in the end I felt like I was being chauffeured on every drive... I got bored with it very quickly.
After realizing Mercedes wasn't for me, I spent the last half of 2015 carefully considering options for my next car. Because of my positive experience with my 525i, I was open to BMWs, but this time around, a manual was on my must-have list. Near the end of my deliberations, I had narrowed the list down to ZHP 330i e46's and bugeye WRXs with the e46 just edging out the WRX because my previous experiences with turbo'd cars taught me that it's hard to stop spending money on making turbo cars faster :D
With a substantial list of must haves, I set out to find a e46. Normally, I would have to make some compromises to get into a car, but I was in no rush and was happy to wait 6+ months for the right car to come along. I came very close to buying one 2 or 3 times but each time I ended up getting undercut by another buyer.
At this time, I'd ruled out later 3 series due to aesthetics (e90) and price (f30) and also all 5 series, because while I enjoyed my e60, I just couldn't wrap my head around a a manual 5 series. It just seemed silly to row a full size sedan. I started to change my mind during the process of shopping for a e46. What I found was that while the e46 market was hot and desirable models / combinations were selling like hotcakes at a premium, the 5series market was in a slump. I kept seeing 5series going for pennies on the dollar and there were a lot of them!
Shortly after being convinced that a manual 5series could be a good thing, I narrowed down my model of choice to a 2002-2003 540i msport with a 6 speed manual. While I'd had good experiences with the 2004+ e60 5series, I've always thought the 98-03 e39 5 series was the better car with the late models being especially good.
However, the 540i has a well known achilles heel that can be very costly to fix when it inevitably happens.
The 540i's M62TU 4.4l V8 keeps time with a chain that is routed from the crankshaft to the heads using a network of guides and tensioners. Unfortunately, these guides break down with age and become brittle. Eventually they break into pieces and the resulting slack in the chain causes the engine to have trouble keeping time. It's not a problem you can ignore and it will eventually destroy the engine if it isn't handled. It's generally considered a 40hr job in labor and can easily cost $4-5k if you pay someone to do it, not even including parts.
It's a serious gotcha, but one I took in stride. After researching the work I would undoubtedly end up doing, I decided to move forward.