The representation of disability is subject to such scrutiny at present that it can seem as if any disabled character is problematic to someone – too sad or too happy, too inspiring or not inspiring enough, and always subject to being read as a symbol rather than a character. Rob Burnett’s sophomore feature (an adaptation of Jonathan Evison’s novel) repeats regular sources of affront: it casts an able-bodied actor, Craig Roberts, as Trevor, who has muscular dystrophy, and then positions him as an instrument for the enlightenment of its able-bodied protagonist, Paul Rudd’s newly qualified carer Ben.

To its credit, the film strives to lift their relationship out of the predictable by foregrounding humour, emotional complexity and baleful physical realities; and both Roberts and Rudd do persuasive work. But as Trevor and Ben set out on a whimsical road trip, convenient symbolism and redemptive cliché drag at their wheels, while a mix of tear-jerking and sub-Farrellys gross-out creates a peculiar tone.

If the film takes a lot of care over its portrayal of Trevor, its treatment of women is oddly shady. Trevor’s mom Elsa (Jennifer Ehle) is presented as a crabby, overbearing matriarch in stark contrast to Ben, despite the fact that Ehle and Rudd are the same age. Trevor’s assumption-confronting sassiness and ordinary bloke credentials are affirmed via his frequently expressed desire to sexually dominate women (‘I would pound that shit into the ground,’ he says of a TV presenter – because that kind of chat is how you know a man is real and relatable, right??).

Meanwhile, hitchhiker Dot (Selena Gomez) is assessed in terms of her attractiveness and vulnerability before the pair pick her up. And a final additional passenger – the stranded solo traveller Peaches (Megan Ferguson) – functions as cathartic plot device only, her late-stage pregnancy and impromptu delivery presented in terms that will have anyone with relevant experience weeping with incredulity.

Screening on Thu 16 and Sat 18 Jun as part of the Edinburgh International Film Festival 2016. Available on Netflix from Fri 24 Jun.