Based on the fact that there are real transactions happening at these prices and 2017 3 series is coming to the lots...
1. Pacific BMW was advertising 6K off all 2016 3 series few days back. It may still be there
2. Concord BMW had 6K off for 2-3 weeks on all their 2016 320i (not 328i) inventory. You could have gotten that without any negotiation. They don't have any inventory on 320i now
3. Some one got 20% of MSRP on 2016 320i (not 328i) as per the link here https://forum.leasehackr.com/t/is-this-a-good-deal-on-a-2016-bmw-320i/3922
4. Patrick BMW is doing ~10% off MSRP on their website for 2016 328i without even asking
So, there are signs out there to point that you can pretty reasonably get 12% off and if you push hard you could get up to 17% or more. You will not know your ceiling until you try hard.
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