Dr. Demetri Yannopoulos, with the University of Minnesota, says the mobility of these machines can save time at a time when every minute matters.

"If we get to these people within 30 minutes, they have a 70% chance to survive," he said.

The SUVs have been out on the street for two months and have already been used in 30 cases. There are four vehicles in the fleet right now, with eight on-call doctors trained to use them.