BAP is, or probably more accurately was, this setup whereby you rented the very expensive traction battery pack of the car for $84 a month for 10 years, and in return (like any landlord is supposed to do) MB would replace the battery pack if anything went wrong with it. You only owned the "sled" (i.e. car without the battery pack). One consequence was that for a while, if you bought a used Smart ED, MB finance could hunt you down and legally _make_ you pay $84 a month for the remainder of the 10-year term - although we never heard any reports of this actually happening.
But that is reportedly all water under the bridge now. MB had so many difficulties with it that they quietly wrote the whole BAP program off.
Which gets us to what you should be looking for. Probably 90 percent of the whole value of an EV is the traction battery pack, so the main thing you should be checking is the health of the battery pack. The first thing you should check is the state if charge it has been kept at at the used car lot, and the temperatures the car may have experienced there. If the car sat with the state-of-charge meter reading 20 percent or less for a long time that is a bad indication, and if it sat like that through a mid-upper latitude US (not to mention Canada) winter - forget about it - the battery pack is probably shot! Also bad, but somewhat less so if is it sat at fully charged for months on end, except of it sat like that thorough a summer in a hot climate area, then you should reject the car too. In fact, if the car is subjected to temperatures below -20C or above 40C (-4 and 104F) at any state of charge, it is supped to be kept connected to a charging station (or the 102V charging adapter) in order to keep the battery pack heated or cooled). in inquiring about this, you will be relying on the honesty of the seller - which of course is something you should never do. And, of course, even the selling dealer does not know how the original owner/leaser (probably the latter) cared for the battery pack...
So, a good way around this would be to do your own check of the battery pack health for any prospective car using this open-source OBD-type diagnostic tool... Just $75 bucks!
http://www.smartcarofamerica.com/forums/f170/smart-ev-battery-test-units-ready-go-144465/
Note that to gt an accurate battery pack capacity indication, the car must have fairly recently been discharged to below 30 percent than fully charged.