When I first started recording I used my car's bluetooth connection to
my Android phone, with AudioRecorder on the phone.  There was a lot of
car noise with this method.  I pretty quickly switched to a bluetooth
device that sits on your ear.  This was a lot better, but had the
annoying problem that it would fight with the car to see who was going
to connect to the phone.  I could not figure out how to tell my car
not to try to connect to the phone.

Finally, the best solution emerged: use a headset with a 2.5mm jack to
plug into the phone (and just turn off bluetooth).  Now I don't even
bother with noise reduction in editing these -- the sound quality is
(in my opinion) perfectly acceptable with this method.