The car ride part is humor correct? If not, that won't help and potentially cause stress.
Going "off" food is completely normal for the species and it is usually the first thing people worry about. IF, and I say IF you have your husband dialed in and there are no signs of illness, there is nothing wrong with a Royal that doesn't eat.
6 months to a year is not unheard of.
The care sheet here and the multitude of sources that discuss this particular species all mention the fact these critters will go off food. People tend to relate feeding snakes to feeding other pet types. It is unfortunate because many reptiles have evolved over several million years to go extremely long periods without food. Most people feed dogs too much food so if you can imagine that mindset and relate it to a reptile you can see why refusal makes you think you are doing something wrong.
Feeding is an interaction between the keeper and the animal and it is human nature to care about your pet. Problems arise when reptiles designed to fast are fed constantly. That may not be what is going on since you didn't mention how often you offer food, or how long the snake has not eaten. 90% of the time the snake, especially this species will resume eating on its own schedule.
Having studied this and seeing it in almost every species I've kept tells me that you have nothing to worry about. You are causing your own stress by assuming a snake of this type needs to be on a "schedule".
How long has this refusal lasted? Were there any traumatic issues during the breeding?
Is the animal kept in a dark room or high traffic area?
Again, unless there are signs of illness, I would ride it out.
Our Royal goes off food almost every year for 7 months sometimes longer. When she is ready, she shows interest, and a lot of it. It took some time to learn this animal and I know what to expect.
We've had refusals from almost every python here. A retic, 2 coastal carpets and the royal. 1 carpet and the royal have been the ones to fast the longest.
The only ones that haven't gone extended periods here are the boa constrictor and the Bredli and I manage them to prevent over feeding.
More information would help.
The simple answer is either there is nothing wrong, or you need to see a specialist.
My thought is the second part would be glaringly obvious.