Some parents are spending 50 hours a month driving their children to school and to social activities, according to a survey.
As many as 19% of mothers and fathers fork out at least £1,200 a year per child on their offspring's hobbies and activities and the transport costs of getting them there, the AA/Populus poll found.
A third of parents lose between 10 and 49 hours a month driving their children around, with 2% spending 50 hours or more on "taxi duty".
London parents are the most prolific spenders, with one in 20 spending more than £200 per child every month on things like sport, music and dance classes.
This equates to a minimum spend for each child of £43,200 over their childhood, up to the age of 18.
The results were based on responses from 6,396 adults with children aged four to 18 still living at home.
Mark Peacock, head of AA Driving School, said: "Mum and dad's taxi is still very much in operation as parents spend large chunks of their time getting their children to various activities.
"Besides taking up a lot of time, parents' driving habits can influence the drivers their children will become later in life so it's important they set a good example on these journeys."