Brighton and Hove is set to become a 20mph city within four years.
Every residential road in the city, apart from the main routes, will have the restrictions introduced by Brighton and Hove City Council.
This means outlying areas including Woodingdean, Saltdean, Patcham and Portslade will all be included in the plans.
The Green administration said the scheme, which police have warned will have to be self-enforcing, will help improve road safety, reduce air pollution and encourage more people to use sustainable transport.
But opposition councillors claim a blanket ban is “over the top”, adding the restrictions will be unenforceable.
Police have warned the scheme will have to be self-enforcing – and that if drivers do not stick to the limit the council will have to invest in traffic calming measures to force them to.
Ian Davey, the council’s cabinet member for transport, said it was consulting on the scheme in response to residents’ requests.
Coun Davey said: “The benefits of a citywide scheme include potentially fewer collisions and less severe collisions while a consistent limit is likely to lead to better compliance, reduced street clutter and safer streets.
If backed in a consultation of thousands of homes, the scheme would take place in stages. The local authority believes it scheme will cost £1.5 million and it is hoped all the work should be complete in the next three to four years.
The widespread zones will be marked with signs and road markings but will not initially include speed bumps or other traffic calming measures.
It was recently revealed a similar city-wide zone in Manchester could cost up to £41 million.
Conservative councillor Geoffrey Theobald said: “We support 20mph zones in certain locations, especially around schools and in residential streets, and indeed, we introduced many of these when we were in administration.
“However, we have consistently argued that the Greens’ blanket citywide approach is over the top.
“It will be difficult, if not impossible, to enforce and my concern is that by slowing everything down it will just end up causing more congestion.”
Labour group leader Gill Mitchell said: “Whilst we fully support 20mph zones we have serious questions as to how the Greens propose to implement the plan.
“They are planning to spend £1.5 million on a blanket city-wide speed reduction scheme based on ‘lines and signs’ only, a scheme that cannot be enforced."
If approved on Friday, consultation is expected to begin in the second week of June and run for about six weeks.