item code and item categories for spare parts

for distributor (car spare parts) :

-- for item code what is the best use number like 01010001

   or use alphabet like HOF01

-- for example

   if we have handles  divide into inside and outside

   and we have multiple cars like mercedes,bmw,hyundai and kia

   inside divide into front and back

   front divide into right and left also back

   also for outside

  handle ---> inside  ---> hyundai

for item code

what is the best hih001

or 0101001

and what is the best for categories ?