Confidence votes 4. The average person will keep their car for 17.46 years. The average car lasts about three years longer than that, but around 30% will sell their car.That's why it's brought down to 17 years.he average person in the UK has braces for around 1 year depending on how bad your teeth are. If they are just slightly crooked or wonky then 9 months - 1 year maximum but, i … f they're really quite bad, you could be looking around 1.5 - 3 years.