The Gulls had a Tony Bedeau goal disallowed in the first half.
And, in a second half which virtually turned into one-way traffic, they hit the post, had another effort cleared off the line and forced City goalkeeper Maik Taylor into a string of fine saves.
It would have been a travesty of justice if substitute Walter Pandiani's stoppage time drive had won it for the Blues, but Torquay's former City goalkeeper Andy Marriott dived to his left to hold the shot.
Birmingham could have had no complaints if they had lost.
Emile Heskey tested Marriott early on and scooped the best chance of the first half over the bar in the 25th minute.
But Birmingham seemed tentative and Torquay more than countered the clear threat of Jermaine Pennant with some sparkling wing play from Martin Phillips and the livewire Jo Kuffour.
Kuffour gave City right-back Alex Bruce such a testing debut that City manager Steve Bruce took his son off midway through the second half.
Bruce Sr was worried enough at half-time that he replaced Jiri Jarosik with Walter Pandiani in attack.
But, instead of seeing his side go up a gear, he watched with growing concern as Torquay tore into his men and dominated the second half.
Steve Woods hit the post with a 25-yard screamer, Martin Taylor cleared off the line from Bedeau and Taylor pulled off saves from Alex Lawless, Kuffour, Hill, Bedeau, Adam Lockwood and substitute Alan Connell.
Martin Taylor was also lucky to escape with only a yellow card after he brought down the fast-breaking Kuffour on the halfway line.
It took Birmingham until the 76th minute to have a scoring attempt in the second half when Nicky Butt headed over.
Marriott had been a virtual spectator before he had to dive to keep out Pandiani's late drive.
Torquay – Jo Kuffour. Tormented Premiership-class defenders with incisive running down the flanks all afternoon.
Birmingham – Maik Taylor. Kept his side in the game with a string of top-class saves and cemented his place as the Blues' number one.