tl;dw:
Modern cars are not as easy to siphon gas out of. You’re going to need a narrow, semi-rigid tube to get past any check valve. Make sure this tube is long enough to reach the bottom of the tank.
Of course, if you’re not concerned about the car, you can punch a hole in the bottom of the tank and capture the fuel that way, but you’ll certainly waste some fuel.
@horse_battery_staple makes an excellent point: If you are uncertain about the quality of the fuel you are siphoning - whether that be because of its age, contaminants (rust/water), or if it has two stroke oil in it, be aware that the vehicle you run the fuel in may run badly, and you may incur mechanical problems, either in the short or long term. Generally speaking, “she’ll run,” especially if you’re cutting the acquired fuel with known good fuel, but you should consider this as an “oh shit” option.
Yeah, I can read, but that’s like totally wrong tho.
When the flap is opened (the doors need to be unlocked for that to happen) an open door indicator is shown on the dash. The cap itself also has a sensor, since this is a safety issue. I think this is even a mandatory feature, if the cap isn’t on you get a “check fuel cap” light on the dash (or it re-uses the out of gas indicator in some cars I think). This feature is even on my 20 year old Toyota Corolla.
That article is super out of date, it’s talking about cars from 20+ years ago.
Edit: And it turns out even my info is out of date again. Apparently cars made in the past year or so actually have fuel tanks without caps and no locking doors. Since the mechanism itself is closed off, no protection of the filler port is needed. So no cap and the door is always unlocked. I have never seen that before, but I haven’t driven any car that new.
But almost every car made in the past 20 years does have a lock on the flap tied into the central locking.
This strongly depends on the car, and it doesn’t necessarily mean that prying the fuel door open while the car is locked will set off the alarm. Some cars that have a fuel door release just use a cable, some use an electric servo that is not tied in with the door locks at all.
That “check fuel cap” light is tripped by the emissions control system checking vacuum in the tank or charcoal canister. It’s not checking the actual cap.