More than a third of 16 to 19-year-olds have been a passenger in a car driven by a young unlicensed motorist, a survey by a safety campaign suggests.
Figures show unlicensed motorists are more likely to have accidents
The FedEx and Brake Road Safety Academy said its finding was "startling wake-up call to parents and young people".
Someone who has not passed their driving test would also be uninsured.
Department for Transport estimates show that unlicensed male motorists aged 17-29 may be up to 11.6 times more likely to be crash than other drivers.
The DfT research from 2003 also indicated they were up to 3.9 times more likely to be involved in a crash than licensed drivers of the same age group.
The FedEx and Brake Road Safety Academy trains volunteers to teach young people about the dangers of unlicensed motorists, speeding, drink and drug driving.
Its survey results were obtained from 700 questionnaires handed out in schools and colleges across the UK.
"Unlicensed young drivers make a conscious decision to drive without the necessary qualification, and often with their cars packed full of young passengers," said Mary Williams, chief executive of the charity Brake.
"They risk not only their own lives, but the lives of their passengers and other road users, and there is an urgent need to crack down on this wide-spread lawbreaking that costs lives through more education and tougher enforcement."
The DfT said the issue was being addressed by a "combination of measures".
Recent initiatives include campaigns in schools run by the Driving Standards Agency and the introduction of more number plate recognition cameras linked to the Driver and Vehicle Licensing Agency database.