After an auto accident is the insurance company liable for a rental car for the entire time you are without a vehicle?

You need to read your insurance policy and make sure you have this coverage. Also this is not enough information to answer your question. Insurance laws are different in each state. In Georgia, if the other party is At Fault then yes the other insurance company will be responsible for the rental vehicle from day one. The problem is that the insurance company will not be able to authorize this from day one. The accident must be reported to the insurance company, the company must get both sides of the story, the police report must be received by the adjuster, and any witnesses must be interviewed. You can understand that this will take time. I always recommend that clients be careful about running out to get a rental car unless absolutely necessary and if they can afford to pay for it. These are a few things that could come up: stories differ, the police report doesn't state clearly who is at fault, your vehicle must be not operable, the person's insurance cancelled, the person driving was not a driver on the other policy or was excluded. So be careful and don't put yourself on the hook for several thousand dollars until you know everything is ok which shouldn't take but a few days for the insurance company to accept liability and ok a rental reimbursement.