Her alleged attacker, also 22, was found hiding in a storage alcove that had been built into the back of the car.
"We would certainly say that what's happened to this young lady is quite catastrophic," Detective Inspector Paul Hart told the ABC.
"When located we will allege that the male person was secreted in the back section of the vehicle which made it quite difficult to find him."
Police say the woman's "very prolonged" ordeal had left her with physical and serious psychological injuries.
It is alleged the woman met the Cairns man three months ago and they agreed to go on a road trip together. But it quickly turned into a long, violent nightmare.
Police say he held the woman against her will and assaulted her at various locations across Queensland between January 2 and March 5.
The attacks occurred as the pair travelled the nearly 1,400 kilometres between Cairns and the Outback town of Roma, police spokesman CJ Roberts said.
The man, from the Cairns suburb of Manunda, was charged with four counts of rape, eight counts of assault, four counts of strangulation, two counts of deprivation of liberty and various drug offences in Roma Court on Monday.
The woman has been treated for facial fractures, bruises and cuts to her body.
A police investigation is continuing while comment is being sought from the British High Commission.
Australia has seen a number of horrific attacks on foreign tourists in recent times.
On Wednesday, a 60-year-old man will stand trial over an alleged sex attack on two female backpackers at a remote beach southeast of Adelaide. The man, who denies the charges including attempted murder and indecent assault, is accused of attacking the women at remote Salt Creek, in the Coorong National Park, in February last year.
And just last week, Queensland police revealed a 24-year-old Polish nanny, who was violently raped while working at Petrie north of Brisbane last year, was killed in a car crash back in her homeland.
She died just days before a 28-year-old man was charged over the vicious attack in a council car park that saw her undergo facial surgery for injuries including a broken nose.
But one of the worst cases in recent years involved the rape of 21-year-old French woman Sophie Collombet, who was left to die on a Brisbane park bench in March, 2014.
In October last year, Benjamin James Milward was jailed for life for raping the student while he was high on ice, and then leaving her covered in nothing but a jacket and a newspaper.
Milward was high on ice when he attacked the young traveller, and she remained alive for several hours as passers-by thought she was a sleeping homeless person.
- With AAP
