The startup Metromile looks to cover Period 1, the time between when an UberX driver turns on his app and when a passenger indicates they want to be picked up. Period 1 has been an issue for Uber. Uber already provides insurance but only once a driver accepts a ride request. Metromile uses a small device that plugs into a car's diagnostic port to track how many miles a car drives. The startup sets a monthly fee plus a per-mile rate