Alright... here's my rationale at the end of the day using approximate numbers for my 135i. For the record, I leased.
Purchase Price: $44,500
Missouri Sales Tax: $2,647
Down Payment @ 20%: $8,900
Cash Outlay (purchase): $11,547
Financed Total: 35,600
60 months @ 5%: $671.82
3 Year Balance: $14,705.29
Estimated Trade-In: $26,000
Estimated Equity @ 36 Months: $11,294.71
Total 36 Payments: $24,185.52
Note here though that my estimated equity (and that's a best-case scenario) is less than my initial cash outlay. Granted a good chunk of this is because of the Missouri Sales Tax. As a result, I am actually losing money during that period that I have the car and lose the opportunity on the money that I'm spending per month.
In real terms here's what I did;
MSRP: 48,900
Purchase Price: $44,500
Doc Fees and Misc: $1000
Maxed MSD's (*7): $4100
Monthly Payment: $595.70
Total 36 Payments: $21445.20
I just put $1000 as a rough estimate of doc and misc fees. Dealers vary. Note here that my initial cash outlay is half what a purchase would be ($5100), but I also get $4100 of that back at the tail end of the lease. That means that in 3 years my cash out of pocket is a lot less with leasing ($22,445.20) as opposed to the purchase ($24,437.81). However there are a lot of other costs that you have to take into account when selling at the 3 year mark which include finding a buyer, for which you must also take into account the cost of advertising, test drives, scheduling... and basically the cost for your time to do so.
Note that I'm also presuming that either way you're going to sell the car at the 3 year mark. This is the assumption I made for myself because I have a habit of doing exactly that. In fact my average is more like 2 years and the lease actually forces me to get rid of my car LESS often. But again that's just me and may or may not apply to your situation.
At the end of the day, it makes sense for
me to lease, but may or may not for you. Only you can answer that question. Be realistic with yourself about what you want to do with the car and how long you're going to keep it.
And for the record, I drive my car like I own it. For better or worse. I figure that wear and tear costs on the car at the end of the lease might eat up some of my MSD refund, but that's fine and a choice I make. I still consider the car mine as much as any car I've financed was mine. I also like the lack of stress knowing that in three years (less now) I'll be able to move onto something new. Maybe a new Bimmer, maybe something else... but probably planning another European Delivery trip. The chance to drive a new and fun little car like the 135i is worth it for me.
Note that the other option; buying cash was not an option. I could've probably bought a 128i pretty much bone stock with cash, but I didn't want that. As it stands, my cash reserves are untouched by the car and are there for any work I want to do on my house in the next three years. My payment is less than I would've had if I had purchased, and I feel that it makes sense for me to do it this way.
YMMV... and I hope this helps