A study from a consumer group found that the largest auto insurers charge "discriminatory" higher premiums to safe drivers than those who cause accidents, mainly harming low- and moderate-income drivers.

The Consumer Federation of America released its third report studying auto insurance premiums, studying policies in 12 cities using the websites of the five largest car insurers: State Farm, Allstate, GEICO, Farmers and Progressive.

Those insurers comprise over half the private car insurance market, according to CFA.

The consumer group collected premiums quoted for two 30-year-old women who had each driven for 10 years, lived on the same street in the same "middle-income" zip code, seeking minimum liability coverage required by that state.

"One was a single receptionist with a high school education who rents, has been without insurance coverage 45 days, and has never had an accident or moving violation," the CFA said in its report. "And the other woman was a married executive with a master's degree who owns a home, has had continuous insurance coverage and has had an at-fault accident with $800 of damage within the past three years."

State Farm quoted the "good driver" less in all 12 cities. State Farm's rates were the lowest in six cities and the second-lowest in the other six cities.

The Insurance Information Institute issued a statement about the CFA's report, saying premiums are determined in part by policyholders' driving records, the type of car they drive and the miles driven each year.

The Institute, which is supported by the insurance industry, said those variables were "downplayed" in the CFA's analysis.

A spokesman for Progressive said the company works to price each driver's policy "as accurately as possible." He said there are ways for consumers to take insurance rates into their own hands, such as through usage-based insurance.

A spokesman for Farmers said the company "does little business in many of the states referenced in this report, which in many ways is misleading."

A spokeswoman for State Farm said it had "nothing to contribute at this time" about the report.

CFA said in 35 of 60 cases studied, large insurers quoted higher premiums to safe drivers, either in excess of $1,000 or refusing to quote a price.

In only four cases did they quote an annual premium of less than $500.

"A fairly high percentage of low- and moderate-income drivers cannot afford to purchase auto insurance, which is why so many risk breaking the law and getting stuck with accident bills," read a statement by J. Robert Hunter, CFA's director of insurance and a former Texas insurance commissioner. "State regulators should ask insurers why they cannot offer more safe drivers basic minimum liability coverage for about $300, and never more than $500, annually."