Can I identify a taxi based on where it was charged on my debit card?

Phone the cab company, explain that you think you may have left soemthing in one of their cabs, and describe where and when you used the cab.
Depending on how long ago this was, the driver may already have checked his cab before going off shift, found the scarf (or whatever it was) and handed it in at their office, or he could still be driving other passengers around without noticing your scarf.

call the cab company and explain, time/date/location/description of car if can remember...