Cars are divided into insurance groups by such things age of car, price of car and make of car.If the car is a sporty car the insurance might feel it will be driven differently that a work, or family car.
Car insurance groups are often regulated through an association and will have to adhere to certain state or federal laws so it is best to check for local groups to find out how they are regulated
"Geiko and state farm are very good groups. To look for the best deals, refer to amazon or walmart would be the best bet. Make sure to check for user reviews though!"
it varies between insure's but in most case's it only goes upto 20 then they offer a 20+ group which meens the insurer can charge you any figure dependant on hw stealable and the actually performance...
Insurance groups negoitiate for lower prices for the members of the group. Therefore if you are a part of the group it will decrease the cost of your insurance.