"Vehicle type as regards radio interference suppression" means motor vehicles which do not differ in such essential respects as:
2.2.1. the shapes and constituent materials of the part of the body forming the engine compartment and the part of the passenger compartment nearest to it;
2.2.2. the type of engine (whether two- or four-stroke, number and capacity of cylinders, number of carburettors, arrangement of valves, maximum power and corresponding r.p.m.);
2.2.3. the position or model of the ignition circuit components (coil, distributor, sparking plugs, screening etc.);
2.2.4. the position of metal components housed in the engine compartment (eg heating appliances, spare wheel, air filter etc.) ...