Do you have shuttles to Detroit metro airport and if so. How much is parking ( we're arriving on a Thursday for one night then flying out and returning on Monday night.)
You should contact the hotel itself for that info.
The hotel itself has a shuttle that will take you to area restaurants and shopping, but not to Detroit.
They will also take you to and from Ford properties.
I did see several vans that appeared to be shuttles on the road, though, so I would suggest you check online for area companies that do run shuttles.
Get an answer from Best Western Greenfield Inn staff and past guests.