State Sen. Barry Finegold, D-Andover, is pushing the state's Attorney General's office to investigate auto insurance companies' practices regarding surcharges.

In a letter sent to AG Martha Coakley last week, Finegold requested that she look into how the companies set their surcharge rates and how the money collected as surcharges is spent, according to an article published in the Lowell Sun.

In his letter, Finegold said that it had recently come to his attention that the methods used by insurance companies to calculate surcharges was not as transparent as it should be.

In a separate letter, Finegold asked the state's Commissioner of Insurance, Joseph Murphy, to require insurance companies to publicly disclose the formula they use for surcharges and privately disclose to each customer hit with a surcharge, how it was calculated, according to the Sun article.