Where did you come up with the figure of $378 a month? Did you make it up? Buying or leasing a car doesn’t work like that. The car needs to fit into your budget, not the other way around. The offer on the table has you spending $21,000 on a car with an MSRP of $27k. That’s idiotic.
When the phrase “No Discount” came into play, did that not strike a red flag?
This dealer is straight up scamming you and it sounds like you don’t understand where to begin the negotiation.
If you’re looking to spend $350-400 a month on a lease I would suggest looking at the market place and finding a broker for a car you want in those ranges, it doesn’t sound like the time it’s worth to get up to speed on negotiation will be worth it.
I was at $399/mo w/0 down for a GTI Autobahn which at the time was like a 36k MSRP. Not a great deal in hindsight, but I really liked the GTI and it fit my need at the time for a hot hatch that was fun to drive and easy to fit into terrible spots at a train station. If you told me I could get a base BMW 328i at the time I still would’ve taken the GTI FWIW.