The Best Car Insurance Companies In New Jersey Ideas . Web the five cheapest car insurance companies in new jersey are geico ($84 per month), nj manufacturers ($105 per month), state farm ($123 per month), amica ($131 per month), and plymouth rock ($132 per month). Geico is also the cheapest company for full coverage at $182 per month, on average. New Jersey Car Insurance Guide Forbes Advisor from www.forbes.com Web the five cheapest car insurance companies in new jersey are geico ($84 per month), nj manufacturers ($105 per month), state farm ($123 per month), amica ($131 per month), and plymouth rock ($132 per month). Web the average cost of car insurance in new jersey is $1,584 2 in 2021 according to thezebra.com. Web best car insurance in new jersey.