Ipswich Borough Council launched a consultation over a new licensing policy in December, running until February this year.
But taxi drivers in the town have warned that strict rules on the level of emissions cabs should have by 2020 could cause financial difficulty - or even the threat of some going out of business altogether.
The borough council's proposals would require cars of Euro 6 diesel, Euro 5 petrol or ultra-low emissions standards by 2020, but in its submission the Ipswich Taxi Tenants Association points out that London and other major cities only require Euro 4 standard.
It also said the short time frame required made it unworkable.
The association said: "If Ipswich council were to introduce a Euro 4 petrol standard, instead of Euro 5 petrol, it would lower the cost of replacing vehicles for drivers who currently drive diesel cars that do not meet the required diesel standards."
It is understood around 70% of station taxis would be affected.
The association added: "A number of drivers have invested in vehicles to see them through until their retirement.
"Now those drivers are faced with paying out thousands of pounds for a new vehicle at a time when work has decreased.
"We accept that the world is heading down a greener path and we are in agreement with this.
"But it's the unworkable timescale and the immediate costs we are objecting too."
But the borough council in its report said that "whilst understanding the financial pressures drivers have, a lower level emission standard does not support the council's air quality aspirations," and added that emissions standards set by the council would need to change every few years.
It is understood an extension to the time period for the new proposals to come into effect could be agreed to help drivers plan for new vehicles and lessen the financial impact.
The council's conclusion added: "Having taken into account the volume and content of the comments made in respect of the consultation, it would be appropriate to balance the financial impact of introducing an emissions standard against the council's aspirations to improve air quality in Ipswich and the need to provide a service to residents and visitors.
"The introduction of an age limit for vehicles would achieve all of these goals whilst being easy to administer."