It was not until early December, however, that it confirmed a deal had been finalised for it to proceed. Citroen, by contrast, has been testing its 2014 C-Elysee for several months.
Hartvelt admits his outfit is under pressure following the delays, but insists they will not derail the success of the new cars, even if pre-season testing opportunities are likely to be extremely limited.
"There is no question we start this programme late, but the thing is we have got an awful lot of experience with setting up a WTCC car," he told AUTOSPORT.
"We also know that most of the laptime is gained in the drawing office and not on the track.
"We're under a bit of pressure - we've done a schedule to build six cars [before the Marrakech season opener on April 6] and it's tough.
"But our intention is to put out the best car possible, and therefore we need to ensure that what we design is right rather than making compromises to get the car out early."
Hartvelt said RML had started preliminary work on the project before its official announcement and also kept it running in the background during the delays, meaning its disadvantage to Citroen is not disastrous.
"We haven't had the 18 months that Citroen has, but at the same time we started some time ago," he said.
"We're confident in our own ability and we'd like to think we can challenge our competitors."
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