Complex sentence: Another myth is that some people believe a Reliant or any 3 wheeled vehicle isn't allowed on the british motorway, this is not the case and any 2,3 or 4 wheeled vehicle is allowed on the motorway aslong as its over 50cc.
Split into simpler sentences: Another myth is that some people believe a Reliant-or any 3-wheeled vehicle-isn't allowed on British motorways. This is not the case as any 2,3 or 4-wheeled vehicle is allowed on the motorway as long as it's engine size is over 50cc.