The network, which was completed last month, has replaced a 45mbps connection with one of 2gbps (expandable to 10gbps) and cut per-megabit costs to 6% of former levels.
It has allowed the Ford-owned companies to guarantee the transfer of design and production information that is vital for car production, as well as the rationalisation of servers across sites, which had been impossible because bandwidth was limited.
In one project to implement hardware for a £750,000 product design initiative, costs were reduced by £150,000 as a result of being able to share infrastructure between sites.
Ron Murdoch, project planning manager for Jaguar-Land Rover, said, "We were running out of capacity and needed more resilience. We started looking two years ago but the cost was prohibitive. Now providers have the cable and it is 50% cheaper than it was then.
"In the past we had to move people and equipment when we initiated projects - now we have bandwidth that puts us at the top of business class and just under carrier class. We have made the wide area network like the local area network."
The implementation is of a scale and resilience that is commonplace in the City of London, but is unusual for an industrial company outside the capital.
It has been made possible by the development of dense wavelength division multiplexing (DWDM) - the latest in high-bandwidth fibre optic cabling. By separating channels into distinct wavelengths, a single cable can give up to 32 channels of 10gbps each, removing the need for multiple cables .
Ian Keene, an analyst with Gartner, said, "DWDM has brought the cost of such high bandwidth connections down. The glut of bandwidth following the telecoms slump has also seen prices shoot down."
The network is designed as a triangle linking the three sites so that if any connection is severed traffic can be routed the other way. No single point of failure has been allowed, with two comms rooms on each site supplied by separate electricity sub-stations. "If we stop communicating, we stop building cars," said Murdoch.
The Lan is based on Cisco equipment. Nortel devices predominate in the Wan. Most of the DWDM fibre is provided by Energis.