I have tried to capture below the summary of my learnings over the last 4 months with trying to buy a great used car (2/3 year old, low milage, mint condition car) specifically in Bangalore. I have also attached an excel sheet of the best cars I found - almost none of these will qualify as a really great deal, so this is more of a "Best of What is out there" kind of list. For context, I did find an OK car at the end of the 4 months -details in the other thread "Finally got my pre-owned hardly used Verna Diesel Rocket".
These learnings are all from first hand experience and I have no links with any of the vendors mentioned. I have tried not to repeat the stuff mentioned in other threads, except for this first one:
1) Look for the top end variants in whichever car model you are interested in. The price difference in the used car market between the low end and the top end variants is small. Also look for cars where the owner has added expensive and useful accessories - e.g. leather seats, premium music system, VKool sunfilm etc.
2) Getting a great deal on a great used car will be very frustrating - exactly like searching for a needle in a haystack. If you find a great car, be willing to give in on the price and be ready to pay about 25-50K more than what everyone advises you to pay for the car. As a guideline, if you get a car at the Carwale recommended individual pricing for a good condition car, you can consider the deal to be great.
3) If you find a great deal, be prepared to move quickly, but don't compromise on any of the steps in the TBHP thread "How to buy a used car".
4) Unless you are looking for a D segment car or above - Civic, Corolla etc., you may be better off buying a new car. The discounting in the price you get is not worth the risk, effort and time you will spend. A few cars you may find great deals in the used car market: SX4, Optra Petrol, Verna Petrol, GETZ petrol.
5) carwale.com and sulekha.com are your best bets for searching online. Owners who list cars directly here generally expect ridiculous prices for their cars and seem very unwilling to negotiate significantly. So do a lot of pre-negotiation on the phone and take the effort to visit only if the chances of a deal happening are high.
6) Dealers are not worth the effort except for the following:
a) Mahindra First Choice Koramangala - Limited selection of cars, but the guys seem very professional, customer focused, non pushy and give an all-inclusive price.
b) Nandi Toyota UTrust Hosur Road & Popular Automatch in Yeswantpur - Good cars, but prices seemed high for every car I saw there.
c) Classic Jayanagar/BTM - If you are looking for a good deal, you probably will not be able to buy a car here because of the atrocious prices they quote, but this is a good place to browse for cars non intrusively - i.e. they have a large selection of cars with a sticker on each of them with all the info on the car including pricing. So you can get a good idea of the used car market here.
d) Trident Hyundai Used Cars, Indiranagar - They seem to have good Hyundai cars at good prices. In contrast Advaith Hyundai used cars are more like Classic's - highly priced.
e) Any of the Maruti True Values - If you are looking for a Maruti, don't waste your time going anywhere else. These guys are professional, have a large car selection at reasonable all inclusive prices and give a 1 year warranty on almost all Maruti cars they sell. I epecially like the unit on the Outer Ring Road (between Martahalli and KR Puram).
5) About the dealer I bought my car from: The Car House Koramangala.
These guys have some great cars - they seem to have a network of rich & famous guys who have multiple cars and change them frequently. But the guys are a bit too pushy and arrogant for my liking. If you are dealing with them, tread with caution, cover every small angle and do not do the deal unless you feel really good about the car and the price. Push them to let you deal with the owner directly and be prepared to walk out if you are uncomfortable (even slightly) at any time