I don't think anybody here would give you 20K for it, but I guess if you say it enough times it must be true...lol. I mean, you have the most knowledgeable domainers in the world who post or lurk here, and NOBODY is going to offer close to 20K.
BMW is such a strong name and brand, that BWM.com seems a bit awkward, and that awkwardness reduces the price a bit. Sure, hypothetically, you can envision a scenario where someone, somewhere pays a big number. But if that is the test, then there is no need for an appraisal forum. Reality has to kick in at some point.
For a 3 letter dotcom like this, the true value is going to be about 25 percent more than the highest offer you would get here, if a reasonable number of people saw it in a sales thread. If, down the road, the stars align and you got double the high offer from here, that hardly makes it worth double the high offer now. There are such things as opportunity costs in this world (and the time value of money). There are plenty of assets that people can buy for 20 to 25K that will likely go up in time. The stock market doubled from the lows of 2008 and 2009, while domain assets have gone down a ton. Great domains have that quality, where time will likely increase their value, but I don't see anyone absolutely NEEDING BWM.com, though I do see two sites on the first page of Google. One is BWMgrp.com and the other BWMgroup.com. It doesn't take a rocket scientist to be able to suggest that it is theoretically possible for one of these two companies to want the name.
However, if they really felt they had to have it to gain a competitive business advantage, then they would have found a way to secure the name before they started their business (and BWMGroup.com is actually less confusing than BWM.com, because you don't have to explain the similarity to BMW). I am probably in the minority here, but I believe that the confusing nature of BWM, which would likely require an explanation (not BMW....not BMW...remember BWM....BWM.com), makes it worth less than what people here are suggesting. The .org forwards to a Bill Winston Ministries site, while the .net is not even functional, so that tells a bit of a story as to how valuable the letters are (not very).
Very very low five figures, only because someone here will jump in and claim to be ready to buy higher if I appraised it a bit lower. The true number that anyone here on this forum would pay you TODAY is far lower than the appraisals that are being so casually thrown out there.