The website, which helps drivers dispose of their cars responsibly, recycles about 400,000 cars annually and in one year found more than £170,000 in change in these cars.
From these figures, and with 32.9 million licensed vehicles in the UK, the site calculated the £14 million loss to motorists. Coins that are found are returned to the Royal Mint.
Website spokesman Derek Campbell said: They say you cant take your money with you when you go but this is exactly what UK motorists are doing everyday on their travels back and forth to work and school.
Through the recycling process the company has found gold and silver and even a Krugerrand coin from South Africa worth £300.
Campbell added: While [£14 million] is an incredible figure its just the tip of a much bigger iceberg. Many coins will be irretrievably lost when cars are crushed and shredded during the recycling process.
Recycleyourcar.co.uk was set up by the Sims Group to raise car owners awareness of the European Unions End of Life Vehicles Directive, which makes the last owner responsible for environmentally sound disposal of the car. It also helps them find their nearest authorised treatment facility.