Can anyone please walk me through how demo (2018?) BMW 320 or 330 lease works?

I’m in Michigan (is that okay?) and we’ve exclusively only leased GM and FCA cars and SUVs due to family employment. Searching inventory, I think I found a handful of 2018 BMW 3 series demos in-state. Has to be 2018, yes? Are there tricks to getting 24 month payment so low? I’d just do a one-time full due up front (unsure if that saves much with BMW). I’ve been reading various threads but didn’t want to disrupt their thread with my amateur questions. Any insights deeply appreciated. Thank you!