A single speed camera caught 1,100 drivers in 24 hours on the first day it was introduced.
Officials have said the traffic calming measure is needed in Plymouth to save lives, but fuming critics have branded it a "cash cow".
More than 23,500 motorists were caught out during an eight week test period - a figure branded "troubling" by a police chief.
From this week those caught face being sent on a speed awareness course in most cases, Plymouth Live reports, although some could be given £100 fines and three points.
The new camera has split locals, however, with some lashing out at the measure.
Carl White, who owns a cafe café owner near Old Laira Road, where the camera was place, branded it a cash cow.
He told The Sun Online : “It is an absolute nightmare, the limit is dangerously slow."
Mr White added: “I think they are doing all they can to rob people.”
But not everyone agreed, with Al Stewart, who lives next to the camera, saying neighbours "love it".
He said: "The main thing is the noise, everyone on the street loves how much quieter it is."
The bi-directional speed camera system on Old Laira Road has been installed by Plymouth City Council following a consultation carried out last year.
Residents told the council they would rather see an average speed system in place than traffic calming measures.
Supt Adrian Leisk, strategic roads policing lead for Devon and Cornwall Police and chair of the Vision Zero enforcement activity group, said: “The results from the cameras’ test period are really troubling and drivers are obviously ignoring the clear 20mph signs in that area.
“Speed is a big contributory factor in serious collisions. Travelling too fast both reduces the time in which a driver can react and increases the risk of serious or fatal injuries in the event of a collision."
A spokesperson for Plymouth City Council added: "We consulted with residents at the end of last year about extending the existing 20mph speed limit. They told us they did not want the traffic calming measures we had put forward, but instead wanted average speed cameras. We listened, redesigned the scheme and secured the extra funding needed.
“This scheme is about keeping people safe on a very busy narrow road. Keep your speed down and you won’t get fined.”
The camera uses ANPR to identify vehicles and calculate their average speed between different camera locations. The camera is capable of working in all weathers and at vehicles’ maximum speeds.
