Birmingham Chamber of Commerce and Industry has joined forces with business leaders in the north-west to urge the Government to press ahead with its #2.9 billion plans to widen the M6.
Proposals are on the drawing board to put four lanes in each direction between the M6 Toll at junction 11a to junction 19 at Knutsford. If it goes ahead it could reduce congestion significantly in both regions.
Both Birmingham and Manchester chambers - suspending their traditional rivalry - plan to respond to a study by Phil Goodwin, professor of transport policy at the University of the West Of England, into the business case for expansion.
BCI chief executive, and chairman of the West Midlands Business Transport Group, Jerry Blackett said: "We have already spent far too long talking about the M6. It is time to act now as doing nothing is no longer an option.
"Widening this stretch of the M6 is vital for the economies of two of the most important regions in the country. There is an inextricable link between economic growth and transport.
"The UK's economy is being impeded by our inadequate and antiquated transport system and congestion continues to cost the West Midlands more than #2.5 billion every year.
"As the Eddington Report found, we need to speed up our planning processes. We cannot afford to spend any more time talking about the M6 while congestion continues to cripple the economy.
"It has taken five years to get us where we are now - which is still no commitment to when the work will start let alone finish."
He added: "While business recognises there are serious environmental issues to be addressed, car engines are getting cleaner to reduce any damaging impact.
"Smooth running, high speed car journeys are a far lesser pollutant compared to the slow, stop-start journeys experienced on congested routes.
"This study must not be allowed to distract attention from the pressing need to tackle congestion.
"Government needs to approve the widening of the M6 and provide the necessary investment to road infrastructure outside the south-east."
Chris Fletcher, policy director at Greater Manchester Chamber, added: "Our members took part in the consultation process in January 2006 and yet here we are half way through the following year with yet another report due on the impact of the scheme with no obvious sign of things moving forward.
"In this day and age it is right that environmental impact is taken into account but this has to be balanced by the damaging effect congestion has on the economy. We are acutely aware of this in Manchester at present with recent plans announced for a local congestion charge scheme.
"The situation regarding the M6 mirrors the fact that poor transport infrastructure harms business and long term economic growth."
Prof Goodwin has been commissioned by Newcastle-under-Lyme Borough Council, Friends of the Earth, Greenpeace, the Woodland Trust and charity Sustrans.
He has been asked to consider the impact of a widened M6 on traffic growth, climate change and the local road network.
Once completed the report will go to the Government to assist decision-making on the subject.