Uninsured motorist (UM) coverage is an add-on to your auto insurance policy that pays for your medical bills after a crash with an uninsured driver or a hit-and-run driver. Most auto insurance policies sold in Texas include uninsured motorist coverage. Essentially, your UM coverage protects you if are in an accident and the at-fault driver has no insurance, or the driver flees the accident scene without stopping. Your collision coverage pays for damage to your car.