Engineering Scope

The scope of aerospace engineering depends on which area you want to specialse in. Like as follows:
HAL (Mostly Aircraft Structures)
NAL (Aerodynamics and Materials)
ISRO- Well ISRO does not have a separate recruitment for Aerospace engineers, you'll have to look into materials, electronics, and structures.
And there are private companies like GE, Honeywell, etc.
Although my suggestion would be to never settle just after Bachelors in aerospace, this is a very vast stream and Masters is kind of mandatory. A Bachelors pay scale may range between Rs. 20,000-45,000 per month. However, a Masters can actually increase the pay by about 3 times.
SPOILER ALERT: The one thing that you would need to excel during your Bachelors is mathematics! I cannot stress this enough, but every subject is a derivative of mathematics. You need to be good-very good at calculus and numerical methods. So please do not take the introductory courses lightly in your first year.
Aerospace engineering requires knowledge about almost all the other branches, be it electrical, mechanical, civil, computers, everything. The scope is really wide because after graduation you can get into any of the fields.

Hello,
After completing class 12th, you need to appear for various entrance examinations. I would suggest you to appear for JEE Mains and Advanced. These two entrance examinations provide admissions to IITs/ NITs and other government colleges, which are cost-effective.
I would also suggest you to appear for individual state examinations (OJEE in Odisha, EAMCET in Andhra Pradesh/ Telangana, COMEDK in Karnataka, etc.). These exams also guarantee you good colleges and serve as a backup in case things don't end up the way you've planned for IIT/ AIEEE.
Every state has its own share of good engineering colleges. So, don't underestimate or overlook them. They can prove to be vital. The more the entrance examinations you appear for, the more the options you will have for choosing colleges.
Certain private colleges like SRM, KIIT - Odisha, GITAM - Vishakhapatnam and ITER - Odisha conduct their own entrance examinations. You can opt for these as well.
After the results of those entrance examinations are announced, if you have a valid score and rank, you can attend the counselling procedure for the respective entrance examination. During the counselling procedure, you can select a college of your choice and the branch of engineering (automobile engineering in your case).
Kindly refer to the link below for colleges for automobile engineering:
https://goo.gl/7yr355
Kindly filter the list based on location and other preferences.
I hope it helps. If so, kindly upvote this answer. If you've any further questions, kindly revert.