My first ever tryst with self driven rented car was on a longish trip to Goa. Since then I have stuck to personal cars and have never bothered renting one. But a lot of people love to take a bigger car on rent and go on multi-day trips. Shrinidhi has a detailed post that answers all the basic questions for the first timer. Is it economical? How much do they cost? What are the risks? etc,..
Santro, Indica: Rs 1300-1500/Day, Getz/Swift: Rs 1800-2000 per day, Ford Ikon, Accent: Rs 2000-2200 per day, Ford Fiesta, Honda City: Rs 2200-2500 per day, Civic, Skoda Octavia, Toyota Corolla, Chevy Optra, Scorpio, Innova: Rs 3000-4000 per day. (note: A security deposit ranging between Rs 5000-20000 will be payable..
Read Self Drive rentals: cost comparison, procedures and more. He has many more stories on self driven rental cars. The post has links to all of them.