I think they're showing fake coverage, if the current level is on display. There are many outdoor spots in Mumbai where airtel doesn't have adequate 2G, yet their map shows blanket coverage across the city.
Already mentioned its showing outdoor coverage only. Mumbai is completely different due to high rise buildings, also airtel 2g is on 1800mhz in Mumbai. Better check their 3g coverage which is on 900 band but again can't differentiate between 3g n 4g.
For places I know have towers is showing same in map. So kind of showing correct info imo.
On road, I have not faced any issues. I do not download so it's mostly maps, photo sharing on twitter/g+ and sometimes a youtube video here and there. has been pretty good. i mean it works great if i stick to 2G indoors for calls and 3G once i get out of the house. no internal feature on android to program the phone to do that automatically could be done with ifttt or tasker i guess.