Hello,

Yes after diploma you can do any Engineering course.

But for admission you have to take lateral entry exam in order to qualify for second year.

Basic requirement for admission is  a candidate must have passed class 12th or equivalent examination with science stream (Physics, Chemistry and Maths). Candidates must have also appeared for national-level engineering.

• For admission in B.E. Automobile Engineering is depend upon the premise of candidate’s performance in a relevant entrance exam, and ensuing round of counselling.

https://www.careers360.com/courses/automobile-engineering-course

https://www.careers360.com/courses/mechanical-engineering-course

You can refer to this links for more information.

Hope this helps!!