It shall be unlawful for any person who is engaged, directly or indirectly, in the manufacture or wholesale distribution only of motor vehicles, whether patented or unpatented, to pay or give, or contract to pay or give anything or service of value to any person who is engaged in the business of financing the purchase or sale of motor vehicles or of buying conditional sales contracts, chattel mortgages or leases on motor vehicles sold at retail within this state if the effect of any such payment or the giving of any such thing or service of value may be to lessen or eliminate competition, or tend to create or create a monopoly in the person or class of persons who receive or accept such thing or service of value.