hi,
Chennai -> vellore -> Bangalore(electronic city - Nice road) -> Mysore Road -> Mandya -> deviate from Mysore road to Hunsur(another KRS dam road) -> Elivala -> Malangi -> GoniKoppal -> Virajpet
Best route is via bangalore only. Until Vellore roads are ok even that portion is part of GQ. From vellore to Bangalore it is super smooth. Chennai to bangalore by car, it will take maximum of 7 hrs. While coming to bangalore, post crossing attibele toll gate(tamil nadu karnatak border), travel around 15 kms, you will nice road. It is again toll road. You can skip bangalore and directly reach Mysore road (In the first NICE road toll gate itself take for Mysore road).
Once you are in Mysore road(even here u can skip Mysore). If you plan for night stay you can plan in Mysore after some sight seeing provided if you start by early morning on 31st. Beware unmarked/hidden spead breakers in this stretch. Trafic will be moderate and local movement will be there since the SH goes via centre of towns on the way.
Post crossing Mandya, start to look for right turn which will take to KRS dam. If you continue on the same road, you will directly reach Hunsur. Dont forget u need to right and then left at Elivala. Enough direction boards are there. Until here is just two lane road and roads are mixed condition.
If you planned to stay in mysore also, you need to come in the same road but from Mysore side. No differnce. Roads are completly two laned and is of mixed conditions. we can do it in sedan. Proceed in the same road, you will reach gonikoppal and virajpet.