It warned that youngsters getting behind the wheel before they were old enough for a provisional licence could then skimp on on-road practice.
That could threaten road safety if they passed their driving test with limited experience on roads.
The study by TRL – the former Transport Research Laboratory – found that despite the popularity of off-road courses, there was little evidence they worked. They involve lessons at privately owned sites such as car parks and showgrounds for children as young as ten.
The research, led by Scottish psychologist Dr Neale Kinnear, said such training “had the most potential for meaningful impact on road safety, however, it also has the greatest potential for harm through adverse unintended consequences (for example, early licensure [obtaining a full licence] and exposure to risk) where delivery is not evaluated.
“There is some concern that without good-quality, controlled evaluation the benefits or the adverse unintended consequences of off-road pre-driver training are unknown.
“In the absence of controlled evaluation, the simplest way to control the risk of harm would be to introduce a minimum learner period.”
The study is part of Scottish Government agency Transport Scotland’s aim of improving attitudes to road safety among drivers before they take to the roads.
It highlighted that one in five injury crashes on Scotland’s roads in 2015 involved drivers aged 17 to 25, including 37 deaths and 293 serious injuries.
The report said: “Young and novice drivers (who have recently acquired their licence) are a high-risk group of road users and are involved in a disproportionate number of crashes.”
Philip Gomm, of the RAC Foundation, which has previously called for a minimum learner period, said: “While recognising the well-meaning motives of all those looking to solve the old problem of young driver crashes, the report is clear that the evidence is just not there to support many of the interventions targeting Scottish teens.
“Better results might come from less focus on the mechanics of driving and more on the life skills needed to resist peer pressure to drive faster on the way home after a night out.”
Neil Greig, the Scotland-based policy and research director of IAM RoadSmart, which is involved with Drive Wise courses for 14-year-olds and over in the Borders, said: “We support a 12-month minimum learning period as part of a graduated driver licensing approach.
“Its benefits are that teenagers can’t rush into passing, they must drive in a range of traffic conditions, such as at night and in winter, and it effectively raises the age for driving to 18.”
A Transport Scotland spokesperson said: “This is a welcome contribution from TRL and we will consider the findings with the aim of informing the future delivery of pre-driver interventions.
“Pre-drivers are a priority focus area and we are committed to improve the road safety knowledge, attitudes and safe behaviours of individuals before they start driving.”