RN
Everyone plans this around one risk: being seen. It is the wrong thing to optimise for, or at least an incomplete one, because being seen is embarrassing and the other three hazards are the ones that put people in hospital, in court, or on a register.
The engine
Leave it off. If you cannot, do not park anywhere enclosed, and check nothing is against the exhaust.
Carbon monoxide is odourless, produces confusion and drowsiness before anything alarming happens, and the confusion is what stops people acting on it. A running engine in a garage is the obvious version. The less obvious versions kill more people: a car idling with the exhaust against a snowbank, a kerb, undergrowth, or long grass, or parked nose-in against a wall with the exhaust close to a corner. Running the heater or air conditioning for comfort is exactly the situation where the engine stays on for an hour with nobody thinking about it.
If it is cold, run the engine to warm the car, then switch it off. Blankets solve this problem completely and cost nothing.
Handbrake on, in park or in gear, and on level ground. This sounds like an unnecessary instruction until you consider that most of the weight in the car is about to move around unpredictably and someone's foot is going to find the pedals.
And the one that should not need saying but did in the original version of this article: not while the car is moving. Not driving, not as a passenger, and not with feet on the dashboard, which turns the passenger airbag from a safety device into a mechanism for breaking both legs and driving the knees into the face. This is not a probability argument. It is the single most consequential line in the whole topic.
The spot
Here is the inversion nobody mentions. The features that make somewhere good for privacy — isolated, unlit, no passing traffic, no witnesses — are exactly the features that make somewhere bad for personal safety. You are semi-dressed, distracted, in a confined space, with restricted visibility, possibly with poor phone signal, having told nobody where you are.
That risk is not evenly distributed, and it is worth being clear-eyed about which of you is carrying more of it, particularly if this is a new person rather than a long-standing partner. Meeting someone new somewhere deliberately unobserved is a different proposition from doing this with a partner of five years, and it deserves a different level of caution: tell someone where you will be, keep your phone charged and reachable, and keep the keys somewhere you could actually get to them.
Practical filters that reduce both risks at once:
- Private land needs permission. Farm tracks, business car parks, industrial estates and forestry roads are owned by someone, and being found there involves a landowner rather than an anonymous passer-by.
- Parks, beach car parks and viewpoints are patrolled, often specifically because this is what happens in them.
- Anywhere with a barrier that closes can leave you locked in until morning.
- Anywhere you could obstruct — a passing place, a farm gate, a fire road — will eventually produce someone who needs to get through.
- Nose-out beats nose-in. If you need to leave, you want to leave.
Windows fog fast in a closed car with two people in it, and a fogged car in an empty car park communicates precisely what you were hoping to conceal. It is not the discreet signal people assume.
The legal category
This varies enormously and it is worth knowing which version applies where you are, because the range of outcomes is unusually wide.
In many places the offence turns on visibility — whether the act was visible to the public, or whether a member of the public was likely to see it and be caused distress. Under that framing a genuinely private spot is a meaningful mitigation. In other places the relevant law applies to any public place regardless of whether anyone could see, in which case seclusion is no defence at all.
The reason to care rather than shrug is the downstream consequence. In some jurisdictions this sits in the same statutory family as indecent exposure, and in a few of those, a conviction can carry registration requirements that follow a person for years. That is a wildly disproportionate outcome relative to the act, it is not the same everywhere, and the only way to know which regime you are under is to look it up for your own jurisdiction. It takes a few minutes and it is the highest-value thing in this article.
Two aggravating factors are consistent almost everywhere: proximity to anywhere children are present, and the presence of alcohol. Both convert a minor matter into a considerably less minor one.
The interior, honestly
A car cabin is a hard box full of levers. Realistic expectations help:
Handbrakes, gear selectors, seat belt buckles, door handles, window switches, seat rails and centre consoles are all at exactly the wrong heights. The back seat is the usable space in most cars; the front is a novelty that mostly ends in someone's back complaining. Reclining a front seat fully and moving it forward opens up more room behind than people expect.
Head-on-doorframe is the most common minor injury here. So is knee-on-console. Neither is dramatic and both are avoidable by not attempting anything acrobatic in a space with a metre of headroom.
Bring a blanket or towel, for comfort and for the upholstery, which does not clean easily and which someone will eventually sit on in daylight. Wipes, water, and a bag for anything used. Do not store condoms in the car — a glovebox in summer gets hot enough to degrade latex, and the packet that has lived there since spring is not the one you want.
Confined space also has a consent dimension worth naming. A car is harder to leave than a room, there is nowhere to step away to, and it is not always obvious to the person suggesting it that the other person feels less able to say stop. Being aware of that is part of doing this considerately rather than a piece of etiquette.
If someone approaches
Stop, get dressed, be polite, do not argue and do not run. If it is a member of the public, apologise and leave. If it is a police officer, cooperate — the interaction being brief and unmemorable is the outcome you want, and arguing on the roadside has never improved anyone's position. Anything beyond that is a question for a lawyer in your jurisdiction rather than for a website.
Realistically
Almost everything appealing about this is the setting and the sense of stepping outside routine, and almost nothing about it is comfort. That is fine — it is a specific pleasure with a specific and fairly short shelf life.
Getting it right is unglamorous: engine off, handbrake on, somewhere legal and not so remote you would not want to be found there, a blanket, and a check of what the law actually says where you live. The rest is just geometry.