Fishers, which has its headquarters in Cupar, Fife, said the sum is the cost of five- and six-year contracts it has signed with vehicle renting firm Ryder.
A typical vehicle used by the company covers around 250 miles every day delivering linen and workwear to customers in sectors such as hospitality, manufacturing and healthcare.
This is the first move in a longer-term replacement programmes, which will also see trucks, tractor units, vans and trailers eventually replaced.
According to Fishers, which can trace its origins back to 1900 and is now majority-owned by London- based Caird Capital, it has now invested more than £12m across the past six years. That includes purchasing new laundry equipment and setting up a low-energy laundry facility in Newcastle-upon-Tyne.
Fishers operates across Scotland and the north of England, with Manchester the most recent destination, to which the company now delivers seven days a week.
Bruce McHardy, managing director, said: "This investment is key to continuing our offering as a national service, delivered locally while at the same time improving our commitment to the environment by lowering our carbon emissions as a result of these vehicles' more modern engines.
"We recognise that our delivery fleet performance is fundamental to providing reliable, flexible services."
Employee numbers at Fishers peak at around 800 during high season for the hotel trade.