Though this old post it popped due to some rating today.
For Howrah Chennai coromondal takes 26hrs journey and 3AC costs Rs 1825 while 1AC costs 4460. Now coming to revenue 1825x72 = 1,31,400 while 4460×24 = 1,07,000. In IR the only classes that get breakeven operating costs is 3AC which means 1AC is lower priced by nearly 15%. So what more IR can provide to travellers.