Their vivid red and blue livery would herald a new era in train travel for cyclists and snowsports fans, providing much-needed extra space to reach the Highlands by rail.
Initial concept designs for Britain’s first carriages reserved for outdoor equipment have been leaked to Scotland on Sunday, showing a multipurpose interior complete with catering galley.
The internal presentation to ScotRail staff details space for 20 bikes in an area which replaces half the seats, with racks at one end for snowboards and skis.
The plans show foldable shelving that could be used for other luggage instead.
Ministers hope the first of five carriages will enter service next summer, coupled to existing trains.
A galley area with bean-to-cup coffee machine and display fridge for sandwiches and cold drinks is also in the designs.
However, the contract for the conversion work has yet to be awarded, which might put back its planned introduction on the Glasgow-Oban line in May.
The final design may also change significantly and there are “no firm timescales” for its completion.
The other four carriages are due to follow in summer 2020, when they would also operate on the Glasgow-Fort William and Mallaig line, and those between Inverness and Kyle of Lochalsh and Wick/Thurso.
They were ordered to ease overcrowding on the routes, where passengers can struggle to find space for their bikes.
John McCormick, chairman of the Scottish Association of Public Transport, said: “They will be a welcome addition, providing some additional seating and an additional toilet, as well as the cycle spaces, for Glasgow-Oban services where demand has been increasing and overcrowding occurs on some services in summer.”
Doug Carmichael, chairman of the Friends of the West Highland Lines, said: “The conversion is well thought out and the café hub is an excellent idea.”
However, he said all passengers should be encouraged to store large bags in the new coach.
He said: “The main complaint, especially on the Oban summer services, is huge stacks of baggage in cycle spaces and door-entry space.”
A ScotRail spokesman said: “We are excited at the prospect of being a part of this innovative project.
“We are continually looking to enhance the experience our customers have when travelling on our trains, and this concept would undoubtedly be a boost for cyclists.
“We are at a very early stage and these designs are only an initial concept, which is subject to change.”
A spokeswoman for the Scottish Government’s Transport Scotland agency, which is in charge of the ScotRail franchise, said: “These early working concepts were drawn up to inform internal and stakeholder discussion.
“The final detailed designs are still under discussion and ScotRail is working to progress this project towards contract award to improve cycle provision across rural routes.”