Research by the University of Birmingham has revealed that a child car seat can harbour twice as much harmful bacteria as the average toilet seat.
Scientists took swabs from a range of safety seats, which are designed to give small children greater protection in the event of an accident, and found an average of 100 potentially dangerous bacteria lurking in each square centimetre.
By comparison, a similar test conducted on toilets yielded just half the number of harmful germs, which include illness-inducing bugs such as E.coli and Salmonella.
The study concluded that vehicle interiors were potentially more hazardous in terms of germs than any area of an average house.
The research was supported by a survey of 2,000 motorists by Continental tyres, which revealed that over half of drivers regularly travel with their vehicles full of clutter. Worse still, one in 10 of the respondents admitted that the mess in their car had caused them to have an accident or near-miss.
Mark Griffiths, spokesperson for Continental Tyres said: "Many people are driving around in vehicles which resemble a rubbish tip without realising the hazards.
"Clutter as well as germs can present a real hazard - for example a can or bottle rolling under a brake pedal would be very serious."
The survey revealed that the majority (60 per cent) of drivers were unaware of the health risks that driving a dirty car could pose, with one in five cleaning the inside of their car just once a year – typically just before a visit to the garage for a service or MOT.
Birmingham University's research showed that the greatest concentration of bacteria was to be found in a vehicle's footwell.
Dr Anne-Marie Krachler, from the Institute of Microbiology and Infection at the University of Birmingham said: "Cars can play host to a number of potentially harmful bacterial species," the Daily Mail reports.
"These germs can easily spread in cars that are not cleaned often, especially if you eat in the vehicle or leave litter and food."