Translation:Do I get off here?
I don't think you use it for planes （飞机）since they don't end in 车 (applied to land vehicles only). For planes it's just 下飞机。
"Should" should be accepted just as much as "Do." It's a more natural question in English.
If you were in a bus or on motorbike it would be 'get off', but if you were in a car it would be 'get out', so they were probably thinking bus but didn't specify.
Why is "where do I get off" not acceptable? Literally, it says "I where go down car".