Better Minecarts

I have the Idea to connect minecarts that would bring a usage to the "Minecart with Furnace" because you can use it as a "Engine" and by connecting minecarts you can make a train for you and your frainds or to transport items because you can connect minecarts with every other minecart lice minecart+minecart with chest or minecart with furnace with tnt minecarts to grief or kill people with them and the furnace minecart could make the train faster but you can dont use it to but it would be slower and you cant go up mountains