Cluttered-up cars are causing thousands of drivers to fail the MOT test.
Some vehicles are not passing the test as the screenwash is not topped up, the survey by Whatcar.com found.
Test centres are also failing vehicles as they have stickers on the windscreen that block the driver's view, while some drivers even turn up for a test sporting no number plates.
Whatcar? said that of more than 285,000 MOT failures between August 2012 and August 2013, a total of 4,649 were for non-topping up of the screenwash.
In addition, 2,852 drivers failed as their cars were dirty or full of clutter and 1,055 did not get their MOT pass as windscreen stickers obstructed the view. Also, 114 presented cars without number plates.
The survey also showed that 4% of the failures were for cars having their first test.
With an average MOT test price of £45, the 10,753 cars that failed their first test amounted to £483,885 wasted by UK motorists.
Overall, the most common reasons for MOT failure were tyre tread depth being below the 1.6mm limit, brake pads being worn down to less than 1.5mm thick, and headlamps being wrongly aimed.
"Many people probably don't even realise that MOT testers can refuse to test your car if it's too dirty or full of clutter."