the average difference between having no insurance history versus five years of high bodily injury and property damage limits (100/300/100) is about $238.
However, I do not have any data for unknown lapses in coverage. An issue you might run into is that certain companies require 6 months of continuous coverage in order to qualify for their company. Your best bet to finding cheap car insurance is to look at as many companies as possible. You can compare hundreds of company with us here.