Fire bosses did not meet “ethical standards” after spending more than £3,700 of taxpayers’ money on petrol to visit family in Scotland.
Gloucestershire Fire and Rescue’s former chief fire officer, Stewart Edgar, and deputy Andy Hermiston used company vehicles to see relatives.
They also spent money unnecessarily on optional extras on “expensive high-end” company vehicles, a report said.
The fire service said necessary steps were being taken to address the issues.
The bosses did not declare their personal mileage, meaning Mr Edgar claimed about 8,300 miles on trips to Scotland as business mileage, at a cost of £1,705 to the taxpayer.
Mr Hermiston made 16 trips to his family home north of the border, and claimed £2,014.
The report found there was no agreed policy in place at the time to differentiate between private and business mileage.
It said the practice of claiming for personal mileage could be perceived as not demonstrating the “required ethical standards” for a person in public office.
The report also found that two Audi Q7s and a Land Rover Discovery were bought for use by the force’s principal officers, costing more than £151,000.
The vehicles had optional extras such as metallic and pearl effect paintwork, and technology packages, costing £8,500.
An investigation into the procedures of the fire service began following a number of whistleblower complaints.
Previous reports revealed a number of policies were not followed, including senior fire officers inappropriately claiming items on company credit cards, and failing to declare gifts and hospitality.
Mr Edgar resigned last year over the sale of a Land Rover, which he undersold then later bought for himself. At the time, an internal investigation found he demonstrated “poor judgement” over the vehicle’s disposal. A police investigation into that incident is ongoing.
Mr Hermiston is still employed by the service.
Gloucestershire county councillor Dave Norman said the reports “make for uncomfortable reading” and showed “some senior firefighters didn’t follow best practice”.
He said he was working with the new chief fire officer and councillors “to ensure the issues of the past are addressed”.