Tevez spent the bulk of last season on strike but has settled his differences with the club and is now back to his best form, scoring for the fourth straight game this campaign and his 50th in the league for City.
The Argentina forward also set up the other two goals, by Yaya Toure and Edin Dzeko, as the team joined surprise packages West Bromwich Albion and Swansea on seven points from three games.
The misery continues, however, for Tottenham and its manager Andre Villas-Boas, who is still searching for the first league win at his new club after a disappointing 1-1 home draw against Norwich on Saturday.
The Portuguese coach was hoping to repair his reputation at White Hart Lane after being fired by Chelsea after just eight months last season, but Robert Snodgrass' 85th-minute equalizer leaves Spurs with just two points from three matches.
After Tottenham was booed off at the final whistle, Villas-Boas said: "I understand why the fans are frustrated ... we will replay their faith. It is only our third game, so it may take some patience."
Swansea missed the chance to climb to the summit above Chelsea by drawing 2-2 with Sunderland, needing Michu's fourth goal of the season to salvage a point.
West Bromwich Albion beat Everton 2-0 to go third on goal difference behind Swansea and ahead of City, while West Ham eased past Fulham 3-0 following an encouraging debut from Andy Carroll after his loan move from Liverpool.
Wigan drew 2-2 with Stoke in the other game.
City was in cruise control in the first half, keeping possession well and deservedly going in front when Tevez's volley was deflected into the path of Toure, who fired home left-footed.
However, tiredness appeared to creep into their display in the second half, allowing Bobby Zamora to equalize in the 59th minute for QPR — the team which City beat in dramatic circumstances on the final day of last season to win the title.
Tevez crossed for Dzeko to equalize less than two minutes later, before the Argentine glanced in the third in injury time.
"What we need to take out of this game was how much character and strength we showed," City captain Vincent Kompany said.
After a 2-1 loss at Newcastle and a home draw with West Brom, Villas-Boas will have been hoping for much more against Norwich, which had conceded five goals in its only other away game this season — at Fulham.
However, Mousa Dembele's 68th-minute goal — a fine effort from the edge of the area on his debut after a 15 million pounds ($23.8 million) move from Fulham — came slightly against the run of play. And Norwich deserved the point earned by Snodgrass' low finish into the corner.
Tottenham finished the game with 10 men after substitute Tom Huddlestone's harsh late sending-off for a tackle on Jonny Howson.
Tottenham was without late transfer deadline-day signings Clint Dempsey and Hugo Lloris, who joined the club late Friday from Fulham and Lyon respectively.
Swansea, managed by Denmark great Michael Laudrup, dropped points for the first time this season but stayed unbeaten thanks to Michu's header in the 66th.
Steven Fletcher, making his first start for Sunderland since his 12 million pound ($19 million) move from Wolverhampton Wanderers, had twice given the visitors the lead just before half time.
West Brom is the other surprise name near the top of the standings after Shane Long and Gareth McAuley scored second-half goals to overcome Everton.
It's been a great start to managerial life for Steve Clarke, who has made his name as an assistant coach at clubs like Chelsea and Liverpool.
"It's been a pleasing start," Clarke said. "I'm beginning to sound like a broken gramophone but the players have been fantastic. They work ever so hard and I think we deserved the three points."
Carroll, hoping to revive his career at West Ham after it stalled at Liverpool following a 35 million pound (then $56 million) move, didn't score against Fulham but he helped set up Kevin Nolan's opener after 53 seconds and was a handful all day for the visiting defence before going off with a hamstring problem in the second half.
Winston Reid and Matt Taylor were West Ham's other scorers in the second half as Fulham began life without Dembele and Dempsey with a resounding loss.