Group 1 Insurance Cars In the UK, car insurance premiums are determined by organizing cars into insurance groups (1-50). The cars listed in group 1 insurance cars cost the least to insure. The factors that determine which cars make it into group 1 include repair prices, safety features, and engine type. in Public bookmarkswith car_insurancegroup_1_insurance_carsinsurance Note: In the UK, car insurance premiums are determined by organizing cars into insurance groups (1-50). The cars listed in group 1 insurance cars cost the least to insure. The factors that determine which cars make it into group 1 include repair prices, safety features, and engine type.