Creating a single fire and rescue service faces major challenges, according to the public spending watchdog.
The Scottish Fire and Rescue Service, due to go live on next April, is said to be expected to generate "efficiency savings" of around £293m over 15 years.
The Accounts Commission says it must overcome weak political leadership, an inward-looking and competitive culture and reduce the high public spending that exists across the current eight services.
House fires and deaths in Scotland are almost double the rate of those in England and Wales, according to the commission report released on Thursday.
While some of this is attributed to higher rates of deprivation, smoking and alcohol abuse, "more needs to be done to understand why these differences persist".
Fewer fires, with fewer resultant casualties, are occurring in Scotland but not at a rate as quick as that seen in other parts of the UK. Five fire services in Scotland are in the six most expensive in the UK, the report also says.
The commission stated: "The costs of Scottish fire and rescue services are relatively high compared with other parts of the UK. This is similar to the pattern for some other public services, such as education and the NHS. The higher rates of fires and therefore higher demands on Scottish fire and rescue services is undoubtedly one important factor.
"In addition, it can be expensive to provide a service to sparsely populated areas and remote island communities. But these factors alone do not explain the variation in costs within Scotland."
John Baillie, chair of the Accounts Commission, said: "There are many strengths from around the country which can be incorporated into the new service. Equally, there are many challenging issues around performance, prevention and staffing which it will also inherit.
"Strong leadership, both nationally and locally, will be needed to deal with the financial pressures facing the service. More attention needs to be paid to finding new ways of engaging effectively with communities and the workforce over service changes that will be needed in in the longer-term.
"All of these factors underline the scale of the challenge, but also the opportunity to create a world-class fire service for Scotland."
A Scottish Government spokesman said: "Every effort will be made to ensure the new single fire and rescue service incorporates best practice from existing services, while strengthening areas where improvements are required."
Liberal Democrat leader Willie Rennie said the critical report is an "amber warning" to the Scottish Government.
"The SNP have got a lot of work to do to convince us that they will be ready for the start date of next April," he said.