A rescue cat arriving in your home has usually spent days or weeks in a shelter kennel, surrounded by unfamiliar smells, sounds, and the stress of other animals nearby. The car ride and the first night are not a gentle transition, they are two acute stressors stacked back to back. What you do in those hours does not determine whether the cat will ever trust you. It determines how fast that trust arrives.
What the cat is experiencing in the car
Cats navigate the world primarily through scent. A carrier, a car interior, and your flat all smell like nothing the cat has ever encountered. At the same time, the motion of a car triggers the same vestibular system that causes motion sickness in humans. Cats do not vomit as readily as dogs in cars, but many experience nausea, excessive drooling, and a flattened, frozen posture that owners sometimes mistake for calm. That stillness is usually shutdown, not acceptance.
The carrier is the single thing you control most. A hard-sided carrier with a removable top lets the cat travel with the top half off and a light cloth over it in the shelter, so the carrier already smells like the cat before the journey begins. If you are collecting the cat on the day, ask the shelter to place a piece of bedding from the cat's kennel inside. That scent is the only familiar thing in the car.
Keep the carrier on a flat, stable surface, a footwell wedged against the seat, or a seat with a seatbelt looped through the handle. A sliding carrier on a back seat adds unpredictable motion to an already overwhelming experience. Drive without music, or with it very low. Speak occasionally in a normal, even tone. Do not open the carrier to check on the cat or to offer reassurance. Every opening is a new threat assessment the cat has to run.
The first room, not the whole flat
The instinct on arriving home is to let the cat explore freely. Resist it. A cat released into an unfamiliar flat of any size will find the smallest, darkest space it can, behind the washing machine, inside a kitchen cabinet, under a low bed, and stay there. That is not settling. That is a cat that has decided the environment is unsafe and is waiting for the danger to pass.
Set up one room before the cat arrives. A bedroom or a quiet room away from the front door works well. Put the litter tray at one end and the food and water bowls at the other, cats do not eat near where they toilet. Add a cardboard box on its side, a low hiding spot the cat can see out of, and the carrier itself with the door open. This room is the cat's entire world for the first day or two.
Place the carrier inside the room, open the door, and leave. Do not coax, do not reach in, do not sit and wait. The cat will come out when it decides the room is safe, which may take twenty minutes or may take six hours. Both are normal. A rescue cat that has been in a shelter for weeks is operating on a compressed timeline of threat assessment. The room being quiet and empty is the reassurance, your presence is still a variable it has not evaluated.
The first night
Most rescue cats do not eat on the first night. Some do not eat for the first twenty-four hours. This is stress suppressing appetite, not illness, and it resolves once the cat begins to feel safer. Wet food with a strong smell, fish-based foods tend to work, is more likely to interest a cat that is mildly stressed than dry food. Leave a small amount out and do not hover over the bowl.
Keep the room temperature stable and away from direct air conditioning. A cat that is cold on top of being stressed will retreat further. If the cat is hiding, do not pull it out. Sit on the floor in the same room for short periods, reading or working on your phone, so the cat can observe you without being approached. This is how cats decide a large animal is not a threat, by watching it do boring things repeatedly.
Scratching, vocalising through the night, or hiding continuously through the first night are all within the range of normal stress responses for a cat in a new environment. A cat that eats nothing, drinks nothing, and has not used the litter tray after thirty-six hours, or one that is breathing rapidly, drooling heavily, or showing signs of physical distress, needs a vet visit rather than more settling time. Stress can suppress a cat's immune system and tip a latent upper respiratory infection into an active one within forty-eight hours of rehoming, shelters call this the rehoming cold, and it is common enough that many vets recommend a check-up in the first week regardless of how the cat appears.
What not to do in the first forty-eight hours
Do not introduce the cat to other pets in the flat during this period. Even a friendly resident dog or cat is an additional stressor the rescue cat has no capacity to process while it is still mapping its own space. Introductions through a closed door, with scent swapping first, come after the rescue cat is eating, using the tray, and moving around the room with some confidence.
Do not invite people over to meet the new cat. Well-meaning visitors who want to see the rescue arrive are a reliable way to extend the hiding phase by several days. The cat needs the flat to be quiet and predictable, and strangers arriving at the door are the opposite of that.
Do not pick the cat up to show it the rest of the flat, and do not carry it to the litter tray to demonstrate its location. The cat will find the tray. Carrying a cat that has not chosen to be held is a trust withdrawal at the exact moment you are trying to build a balance.
The first forty-eight hours set a pattern the cat will generalise from. A cat that learns this flat is quiet, that food appears reliably, that the large animals here do not chase or grab, will extend that learning to the rest of the flat when it is ready. The expansion happens on the cat's schedule, not yours, but the schedule shortens considerably when the first hours are handled without pressure.