How to send contact via bluetooth?

You cannot permanently transfer them to the car's memory. If the car's hands free supports PBA, then it can browse and use the contacts on the iPhone for making calls, but the iPhone does not support any form of permanent contact transfer.

Check your cars system manual about PBA and how to get it to work.

Not possible as the iphone does not support the bluetooth protocols to do that It does support HFP (hands free) and PBA (phone book access), which allows another hands free device which supports PBA to look at and use the iPhones contacts while the devices are paired. But the iphone's contacts cannot be transferred to another device by bluetooth (iPhone has never been able to do that).