The Automobile Association's principal adviser for infrastructure, Barney Irvine, said lower speeds in a lot of CBD streets was a no-brainer where there were many pedestrians and distractions.
But on busy multi-lane streets like Hobson, Nelson and Fanshawe Sts that connected to motorways, reducing speed limits might not be the answer, he said.
"There's a risk on these bigger roads that we change the speed limit, but don't get the compliance, because 50km/h still feels like the natural driving speed," Irvine said.
Auckland Chamber of Commerce chief executive Michael Barnett agreed with plans to reduce road deaths and injuries, "but with limited resources it's important that the safety spend is where they can get the best result not the best headline".
AT's group manager of network safety Randhir Karma said average speeds along main roads in the CBD were generally below 30km/h already, which would not impact driving times, but there were points that had higher speeds.
"These are not appropriate when we have a high number of people walking and cycling.
"If a person walking is hit by a vehicle travelling at 30km/h, the chance of dying is 10 per cent. At 50km/h, the chance of dying is 80 per cent," he said.
Earlier this month, AT board chair Lester Levy and chief executive Shane Ellison presented their speed management intervention programme to council's planning committee where it received unanimous support.
It is based on "Vision Zero" principles, which emphasises that no loss of life on roads is acceptable and accepts that road users make mistakes.