When a driver gets in a car accident with another vehicle and the driver of the other vehicle is at fault, it is generally assumed that the at-fault driver’s insurance will cover the cost of the accident. What if the at-fault driver is uninsured or underinsured? What if the at-fault driver hits and runs? Who pays then?Drivers have the option of adding uninsured or underinsured coverage onto their auto insurance policies. When a driver has opted for this type of coverage, he is covered under his own insurance policy if he is involved in an accident with someone who does not have adequate insurance.One option with some uninsured or underinsured auto insurance coverage is something called stacked or stacking coverage. Stacked/stacking auto insurance is an option if a driver has more than one vehicle that is being insured on a single policy. Let’s say a driver has three vehicles on a policy and opts for uninsured/underinsured coverage at $50,000. With stacked/stacking coverage, each of the three vehicles has $50,000 coverage.An advantage to having stacked/stacking auto insurance coverage is that even if only one of the three insured vehicles is in an auto accident with an uninsured or underinsured driver, the entire amount of coverage (in this case $150,000 for the three cars) is available to cover damages and bodily injury for the one accident. This can be beneficial if the damages done in the accident, particularly bodily injury damages, exceed $50,000.Stacked/stacking auto insurance coverage usually costs more, sometimes 10-30% more than non-stacked coverage because the benefits are increased. Although only some states require drivers to carry uninsured/underinsured coverage, it is beneficial for all drivers to consider carrying this type of coverage so that they are not left uncovered after an accident. It is also beneficial for those who choose uninsured/underinsured coverage to consider the stacked/stacking option. Drivers can check with their individual insurance companies to find out if this is an option on their insurance.Get multiple free quotes here at AutoCarInsurance.org on stacked/stacking auto insurance coverage.