Connected and Autonomous Vehicles (CAV) could bring significant societal and environmental benefits, from making traveling safer, cheaper, and more comfortable, to increasing access to mobility for the elderly and disabled. A key element of the ‘mobility revolution’ is developing wireless communications that allow vehicles to talk to the driver, to each other and to roadside infrastructure. The cost-benefit analysis for a particular type of communications technology, Dedicated Short Range Communications (DSRC) illustrates the benefit to society and the environment in terms of improved mobility, safety and air quality against the cost of developing and implementing the technology on motorways and urban roads.