You don't have to get the oil changed because it's low, you can add some in to hold you over to the oil change interval. I assume you are due for a change, but, it's not 100% clear.
Anyway, I had good luck at Super Walmart but, I don't own a fancy foreign sports sedan so I don't know if they'd have troubles with one. The price for Mobil-1 oil change was el-cheapo and you can watch what they are doing if you like. They might not carry the right filter for a BMW, and they didn't offer the synthetic filters I've gotten elsewhere. Still if you change your oil frequently, the filter or the oil is not likely going to be a problem (the crappy ones have worked for years and years). I just prefer the extra insurance I get by using FULL synthetics.
I've also had good luck at the Mobil Gas dealer that has an OilChange drive thru, but, it's too far from where I currently live and it costs a bit more AND they are doubtfully any better than any other jiffy lube place.