I did my BBA in 2013. What is the procedure to pursue Diploma in automobile engineering?

Yes, you can apply for admission in BBA and after completion you can apply for MBA. Diploma in automobile engineering is definitely more than class 12th and will surely make you eligible for any degree course. Just make sure you perform well in the entrance exam conducted by the concerned university

You just have to approach a nearby Polytechnic for admission. Since you are a BBA graduate, then that means you are already eligible. To get a good college, you will have to apply for Entrance exam conducted by your state. Or else just approach a private college for admission.

For pursuing Diploma in Automobile Engineering, you have to complete your class 10th that's it. And, if you have completed your class 12th, that too is fine. For college nearby, you can check Shiksha. Com.