One in 10 parents who live within 500 yards of their child's school admit driving them to the school gates, according to research.
Data also suggests that more than half of British school children will not be walking to school when term starts next week.
A third of children who get a lift to school live less than a mile away, according to the survey by parenting website parentdish.co.uk.
Around two-thirds (68%) of parents would rather their children walk to school but give them a lift because of time pressures, according to the research conducted among 2,000 adults with school-age children.
Tamsin Kelly, editor of parentdish.co.uk, said: "Jumping in the car for the school run may be the easy option, especially when we're all so time pressed, but leaving a little more time to walk to school really does reap rewards for everyone.
"It's a time to give your children some undivided attention without the demands of home and work, and a brisk walk really does set them up for the start of the day."
Meanwhile, separate research finds that a third of Year 6 children are obese or overweight. Four-fifths (80%) of primary care trusts (PCTs) in England report an increase in the number of obese children aged 10 and 11 over the past five years, data analysts SSentif said. Just over a third of PCTs report an increase in obesity in children aged four and five.
More than a quarter of children living in the London Borough of Southwark were classified as obese in 2011, said SSentif, which analysed statistics from the Health and Social Care Information Centre and the National Child Measurement Programme. Richmond and Twickenham PCT has the lowest percentage of obese children but still has one in 10 children classified as obese.
Judy Aldred, managing director of SSentif, said: "Childhood obesity is one of the most pressing public health concerns we have to tackle and yet rates have increased over the last five years, despite the Government's attempts to curtail them.
"We've just hosted a fantastic Olympic Games and the legacy of those Games has to be to improve the health and fitness of our children. This is the perfect time to focus on this issue and to take steps to tackle the problem."