Hawke's Bay regional leaders are the latest to complain to government ministers over funding to transport agency Waka Kotahi.
They follow a suite of other mayors, such as Neil Holdom from New Plymouth and the body Local Government New Zealand who have expressed concern around how the transport agency operates.
The speed limit on much of State Highway 5 - the road from Napier to Taupō - changed to 80 kilometres an hour from 100 earlier this year. Speed reviews are on the way for most of the region's highways from next year.
"The regional leaders across Hawke's Bay are united in our deeply held concern that Waka Kotahi is literally putting the brakes on our regional economy, through its approach to speed management on the state highway network'' a statement from them read.
"Indeed, this problem highlights a deeper 'urban bias' across the state highway network, where the Bay of Plenty, Auckland, Wellington and Waikato Regions enjoy 100 or 110 km expressways and motorways, along with Government investment priorities for rail being confined to the major centres."
"Non-urban regions, particularly in the central and lower North Island, are being disadvantaged under the new 2022 speed management guideline, that imposes 80 km/hr limits on their state highways which are critical transport corridors.
Legal action against the decision to lower the speed on the Napier-Taupō Rd was still an option, but they thought "the problem with a legal action though is that if the High Court overturned the State Highway 5 decision, we fear Waka Kotahi would just make the same decision again, and now under the new 2022 guideline, which seems to make 80 km/hr, essentially mandatory."
However, the region's transport committee chair Martin Williams told RNZ the leaders were not out to criticise Waka Kotahi.
"This isn't just a beat up on Waka Kotahi, I mean they are somewhat the fall guy here. They are operating within funding constraints and trying to keep our road safe, which is why we've directed this at the next level - at central Government itself.''
They are demanding an urgent meeting with ministers to discuss matters pertinent to the region.
The letter was sent to Grant Robertson, Nanaia Mahuta, Stuart Nash, Michael Wood, Meka Whaitiri, Kieran McAnulty and Anna Lorck.
Minister of Transport Michael Wood is overseas in the United States.
In a statement, Acting Minister of Transport Kieran McAnulty said he had received the letter in Wood's absence.
"I'll be acknowledging the letter in my capacity as Acting Minister of Transport, and Minister Wood will be engaging with the councils on this issue. I'll be supporting Minister Wood as one of the local MPs in the area, as we work alongside the council."