The 9.6-mile Silver Line Bus Rapid Transit system kicked off this week with free rides to attract commuters.
"This is important today for symbolic reasons," Mayor George Heartwell told WZZM-TV at a ceremony marking the service's start. "We're the first in the state of Michigan to have bus rapid transit. We are looking toward the future. We're not stuck in the past, we're not even stuck in the present."
The federal government paid about $32 million of the costs, and the state paid about $8 million.
The system cuts a typical 45-minute drive to a 27-minute commute, according to transportation planner Conrad Venema.
Supporters also said the Silver Line will foster future economic, housing and transportation development. They hope the line will replicate the success of Cleveland's bus rapid transit system, which has stimulated about $6 million in development since 2008.
Jeff Steinport, of the Kent County Taxpayer's Alliance, said he thinks the new bus system is a boondoggle that duplicates existing public transportation routes.
"A quarter of existing routes are faster," he said. "It's not really that big of an improvement."
The National Transit Database said the city's traditional bus system had 11.9 million passenger trips in 2012. That's up from 10.8 million in 2011 and 9.7 million in 2010.
Venema and other officials said they expect the addition of the Silver Line to increase the number of riders. They said the system will eventually be able to serve 5,000 riders each weekday.