When a RideableMinecart turns 360° it gets a buggy.

First of all. I'm a turkish minecraft player so my english isn't very well.
1. I realised when you stand top of the Magma Block (block in the nether) if you press SHİFT you don't take damage

2. I did a command block structure that makes minecarts turn around 360°.
But when it turns 360° it gets a bug (like i said i can't speak english very well) please fix it.