Another example of the Metric Monsters taking a simple concept and turning it into meaningless mush.
The 'Board Foot' does make sense, if you're buying large quantities of lumber. But for the hobbyist who wants a particular board, which has maybe a couple of fairly random edges and maybe a big knot at one end, the yard guy with the measuring stick is either his friend or his enemy...the hobbyist is at his mercy. If Y.G. says it's 3.7 B.F. that's what you're going to be paying for.
The concept of M3 is complete b.s., unless you're buying full lifts, or railcar loads.
For framing lumber, on the other hand, where each piece is the same size, the alternate price per running foot (or metre) makes more practical sense 20 pcs-12'/2x4 @ $.50/linft... 20x12x.5= price
Sure the yards' computers will have the B.F. price, but they also have the conversion factor.
I doubt that you could even fit a M3 into a small car! That's a lot of weight. You're always going to end up with a M3 volume of something to two decimal places (.05 M3 for example) if you're buying small amounts of lumber.
As I've argued before, metric has no connection to the Human experience. Trust the French...