The incident happened at around 10.40pm, outside the Cheeklaw Garage on Station Road.
A Renault Espace was set on fire before the flames spread to a Volkwagen Passat, which was parked nearby.
As a result, both vehicles were completely destroyed.
Members of the public who remember seeing any suspicious activity around the garage on Wednesday evening are asked to come forward.
Chief Inspector Kenny Simpson said: “This mindless act of destruction has left two vehicles with irreparable damage and we are keen to hear from anyone who can help us identify those responsible.”
Those with information are asked to contact police immediately on 101 or make an anonymous report via the charity Crimestoppers on 0800 555 111.