Classic cars which were built or first registered over 40 years ago do not need an MOT test as long as they meet certain criteria. As part of this exemption, vehicles must have had “no substantial changes” over the last 30- years to qualify.
The guidance says: “You need to check whether the vehicle has been substantially altered in the last 30 years, checking against the criteria.
“If it has been altered substantially a valid MOT certificate will continue to be required. If you are unsure check, for example from an expert on historic vehicles.
“If you buy a vehicle, we also recommend checking with the previous owner if you can.
“The registration number of a vehicle should not be used to determine if the vehicle is a VHI (Vehicle of Historic Interest) as it may not reflect the vehicle’s age (cherished transfers, reconstructed classic vehicles etc).
Alterations to the suspension and steering are considered substantial changes as these can adjust the way a car handles.
Any updates which have changed the number of cylinders in the engine from its original format is also likely to be a substantial change.
Vehicles which have been given a Q registration number or a model which contains parts from a kit car would also fail to meet the exemption criteria.
A reconstructed classic vehicle or a kit conversion will also be considered a major change to the vehicle
However GOV.UK warns anything made to preserve a vehicle because the original parts are no longer available would be allowed.
Any changes which were made when the vehicle was still in production or within 10 years of the end of production will also not have been substantially changed.
To avoid being unfairly caught out and penalised, GOV.UK urges drivers to speak to a historic vehicle export after making any changes.