Originally, when you sold a car, you had to complete the V5 form and send it to the DVLA to show you no longer own the car or the same when you bought one. But the DVLA have had a big push ongoing digital and you can now submit this paperwork via the internet. You can log into https://www.gov.uk/sold-bought-vehicle and answer the questions there to cut out the need for you to return the V5 paperwork. You will need new owners details including an email address to do this. However, the DVLA will still issue a new V5 and this will be sent in the post so watch out for this after you have completed the online form.