Based on the information provided, it appears that USAA offers the cheapest full coverage car insurance policy without unfair price hikes. According to the data, USAA's average full coverage car insurance cost is $1364 per year, which is lower than the national average of $1556 per year. Additionally, USAA's rates are lower than those of other major insurance companies such as State Farm, Geico, and Travelers.
It's worth noting that USAA is only available to military members, veterans, and their families, so it may not be an option for everyone. However, for those who are eligible, USAA appears to offer the cheapest full coverage car insurance without unfair price hikes.