Section 54C. Any company authorized to transact the kinds of business specified in the first or second clause, or in subdivision (b) of the sixth clause, of section forty-seven may insure against any loss of or damage to, or loss of use of, or mechanical failure or mechanical breakdown of motor vehicles other than motorboats, or aircraft, their fittings or contents, or against legal liability for loss or damage on account of injury to or death of any person or on account of any damage to property of another, arising out of the ownership, maintenance or use of said vehicles or aircraft, provided it maintains a surplus to policyholders including any guaranty capital, of not less than six hundred thousand dollars.