If you have decided on going for a diesel entry-level C-segment car, then by far the best option is Indigo. I went in for my third Tata car (after Indica DLX in 2003 and Indigo GLX in 2005) in Jan 06, and believe me, I have never been happier with any other decision I have ever made (other than perhaps leaving Bangalore for Hyderabad :). I have driven the car for 1800 kms now.
In its new BS-III TDI (Turbo Diesel with Intercooler) avatar, the car is a joy to drive, with the turbo kicking in delightfully at the right revs to give you that extra nudge and adrenaline rush (especially on the wide, spacious roads of Cyberabad - there I go again! :). The turbo unit and intercooler have a huge resonator built into the roof of the bonnet.
The overall build quality is quite good, though there can be some minor improvements.
The engine and gearbox function near-perfectly, and the AC is flawless. They may not be as quite as their petrol counterparts, but for auto enthusiasts like me, theyre the all-important indications of a live and kicking beast that is caged under the hood (72 turbo-horses, to be precise). The muffled hiss of gasoline engines, on the other hand, is equivalent to death (or something very near it), and the reduced NVH in the cabin is best described as the stillness in a morgue.
The dealer Concorde Motors in Khairatabad, Hyderabad, was a delight to transact with. Whats more, 3 weeks back, the company officials recalled my car to replace some power-steering pump worth approx. Rs 7000.00 free of cost! And to imagine, I didnt have ANY complaints about anything!
The car handles beautifully even at 90 kmph that I touch everyday on my way to office, thanks to the wide open roads in Cyberabad (someone stop me!).
I am averaging a stupendous mileage of 13.5 kmpl in city with AC!!
The new beige-coloured interiors are a delight, as are the new 2006 body colours - mine is the new Starry Gray. The roominess inside is easily D-segment!
After my long experience with Tata cars, I can perhaps confidently claim only now that Tata cars have finally arrived. They are seriously knocking on the doors of international-quality-cars, and some important components like the mechanicals are already there.
My advice: Just try one!