I have just one idea that came to me about when the adjustable wheels and engines came out. That idea would be some sort of hub that you could attach parts to and it would be connected to an engine. An example of how this could be useful is connecting wings to it and making a simple helicopter. I would really like to see this implemented into the game and I hope that you guys would agree.
I'm looking foward to 1.6.
Oh thank god I thought you were going to say multiplayer