It really looks like shit dude, but it`s not so bad for a beginer i think you should practice more on diffrent materials and try to make a sketch and bulid your model after the sketch. You will advance and get better if you practice alot.
For someone not from an arts background, I think this is pretty damn good.
Advice: Take a sculpture class at a local school. I’m not familiar with the education system of India, but there must be somewhere you can take an art class cheap. This will give you the basic techniques of working with clay and other materials that you can’t learn very easily on your own.
After that, get your hands on the real automotive clay. It might be hard to get it in India though. I know here in Canada it is not available widely, and more expensive than other clays. I’ve seen it used though, and the difference is huge. Also, the real auto designers cover their clay models with a thin film that gives the appearance of paint, versus your model which appears quite rustic.
As for design, try sketching a few more cars before your next model. Try drawing lots of existing models and try figuring out what works and why. Taking some courses in design would help too.