It's through Chrysler/Fiat - I just dug out the contract. At the top it reads:

"Chrysler Group Service Contract Application"

Then in the line item section:

"CHRYSLER SERVICE CONT
999 MOS 999999 MILES"

da only maintenance ive done is routine stuff. oil changes, air filter changes, cabin filter changes, blinker fluid changes, brake fluid changes, coolant changes, tire changes, exhaust changes, mines rear spoiler changes, ings+ front lip changes, cs mirror changes, so on and so forth. just routine stuff

I've owned two E34s (530, 535) and currently drive an E39 (540) so I'm very familiar with a BMW's true cost to own. They're amazing cars but over-priced. Replacement parts are even more ridiculously priced. I replaced the key and HVAC buttons for the 540 a few months ago and I spent almost 400 Euros. I would never, ever, keep a BMW past the warranty period unless it's an M car I intend on keeping forever. We recently picked up an F30 (320), and though it serves its purpose very well, it'll get traded in before the warranty goes out.

Things to watch out for:

Leaking Differential Bushings, replace with aftermarket as Nissan ones are junk and will leak again.
Steering Lock Failure, was supposed to be fixed via recall but beware late 2010's like mine that aren't covered under recall but still failed. :/
Clutch Slave Cylinder failing and not being covered under the POWERTRAIN warranty (I mean come on, I was stranded 4 hours from home and you tell me its not powertrain)

But to be honest, I have a friend who drive a 5 series and the maintanence cost is much much higher for him than me. Plus I have done all of these repairs (minus the Slave cylinder) myself in my driveway with my father as projects so Yes you can do the wrenching yourself if you have the time and the drive.

Overall, with all the issues I've had, I don't ever plan on selling this car, it's just like my motorcycle, it might break in weird ways sometimes but the unique special feeling I get from driving it is worth it.