What should be done with genuine vehicle registration plates in a photograph?

I have some photographs of vehicles that will be used on a website. I was previously planning to only blur out the registration numbers on vehicles not owned by the company, but it recently came to my attention that they'll be changing these vehicles and there's a possibility the old vehicles will be sold to a new owner.

I'm not really worried about any legal ramifications. I just want some sensible advice.

I can think of three options:

1. 
   

   Blur the vehicle registration numbers.

   
   


2. 
   

   Blank the registration plates to their background colour.

   
   


3. 
   

   Leave it and don't worry.

   
   

If you know of more options please suggest them. Altering the numbers/letters on the license plates for each and every photograph would be too much work.

What should I do about genuine license plates in a photograph?