The news comes as an accompanying survey finds the vast majority of drivers do not understand all road signs.
A study of 50 licence holders asked to take the theory part of the test found half failed the multiple-choice section. A further third failed the hazard perception element.
Candidates must correctly answer, within 57 minutes, 43 of 50 multiple-choice questions which are selected at random from more than 1,000.
The hazard-perception part of the test, which involves 14 one-minute video clips, requires a pass score of 44 out of 75 points in 20 minutes.
Both parts of the test must be passed to get a licence.
Drivers in the mock test found questions about road signs the most difficult, followed by those on vehicle handling and accidents.
A separate poll of 2,000 people also showed only 15 per cent of drivers felt they fully understood all the road signs they encountered when driving.
Among those who felt unsure about the signs, more than one in three had crashed or broken the law.
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Just over half thought drivers should have to retake the theory test at some point after passing their driving test. A retake at just over ten years was the most-favoured option, with 8 per cent saying the test should be retaken every five years.
Steve Barrett, head of Churchill Car Insurance, which commissioned the mock test and poll, said: “An inability to read the road properly often leads to hesitant and unsafe driving behaviours, so we’d urge all road users to regularly brush up on their knowledge of road signs and regulation, as these are frequently updated.”
AA president Edmund King said: “With most skills in life, there is a continual training process. Professional footballers don’t stop training and learning once they have made the Scottish Premier League.
“Other professionals likewise need to keep up with changes.
“Drivers shouldn’t stop learning once they have passed their test. We advocate post-test training to develop new skills, such as driving in more extreme weather conditions or to keep up with changes to the Highway Code.
“Driver training can be fun and incredibly useful. More drivers should try it.”
Neil Greig, the Institute of Advanced Motorists’ Scotland-based director of policy and research, said: “Older drivers are one of the safest groups on the road. Most drivers instantly forget the Highway Code the moment they pass the test. A more accessible Highway Code would be a more useful first step before compulsory retesting.”
Ian McIntosh, chief executive of RED Driving School, which conducted the mock tests, said: “It is very worrying that road illiteracy amongst experienced motorists is so widespread. The theory test is an essential part of a driver’s road education .[It was] introduced in 1996, so there will be a lot of drivers on the road without this grounding.”
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