good car for first time buyers

I am using this car since almost 3 years. Clocked about 37 000 KM. One good thing about this car is its low cost of maintenance , spare parts. Milege after 3 yrs of using still amazing- i am getting about 18 + with AC on at Highways. This car i have tested upto to 124 KMPH speed on Chennai Bangalore highway. Thouugh it is little bit shaky at high speed it is manageable.

AC is not good. rather very bad.., Pick up reduces drastically when AC is ON. While overtaking we must swithcu OFF. Very less rear seat leg room.

I am planning to up grade to Sedan.., any suggestion from my friends?? I am planning either Indigo CS for better space OR desire for better performace.