As you have completed diploma in automobile engineering , you can do B.tech in either Electrical engineering or Mechanical engineering where these two will be similar to automobile engineering but not totally.

Automobile engineering is based on designing.So, you can also learn courses like CAD,CAM,AutoCAD..

I personally suggest you to take Mechanical engineering because it is such a beautiful subject consisting of machines and all that & those are related to automobiles too.

Feel free to ask about queries.All the best..!! 

Thankyou.

Hello aspirant,

1Computer science and engineering
2Electrictrical and Electronic Engineering
3Electrictronic and communication engineering
4Civil engineering
5Computer science and engineering
6Mechanical engineering
7Chemical engineering

Hope you understand,
Thank you

Well,you should go for automobile or mechanical engineering it will be best option for you.