Learn Hardcore Indonesian: Saya sedang belajar mengemudi mobil.

sedang marks an action in progress (similar to English “be … -ing”).
It’s optional. Without it, Saya belajar mengemudi mobil can mean “I learn/am learning to drive a car” in a more general or habitual sense. With sedang, you emphasize “right now/at the moment.”

Can I replace sedang with lagi?

Yes.

Saya lagi belajar mengemudi (mobil). = natural, conversational.
sedang = neutral to formal; lagi = casual.
Note: lagi can also mean “again,” but when it comes right before a verb phrase (e.g., lagi belajar), it means “in the middle of.”

Where does sedang go? Can I move it?

Place sedang before the verb phrase, typically after the subject:

Natural: Saya sedang belajar mengemudi mobil.
Unnatural: Sedang saya belajar… (sounds poetic/marked)
Don’t split the verb phrase: avoid Saya belajar sedang mengemudi…

Do I need a word for “a/the” before mobil?

No articles in Indonesian.

mobil can mean “a car” or “the car,” depending on context.
If you must stress “one,” use sebuah mobil, but it’s often unnecessary in everyday speech.

Can I drop mobil?

Yes. Saya sedang belajar mengemudi is fine and commonly means “I’m learning to drive (a car).” Add mobil when you want to specify the vehicle type or contrast it with others (e.g., truck, bus).

Is mengemudikan correct? What’s the difference from mengemudi?

Both are correct.

mengemudi (mobil) = to drive/operate (often fine with or without stating the object).
mengemudikan (mobil) = explicitly “to drive/operate something,” slightly more formal/explicit.
You’ll often see mengemudikan with aircraft/ships: mengemudikan pesawat/kapal.

What’s the difference among mengemudi, menyetir/nyetir, and mengendarai?

mengemudi: standard “to drive (a vehicle),” slightly formal-neutral.
menyetir/nyetir: everyday “to drive (a car).” nyetir is casual/colloquial; menyetir is neutral.
mengendarai: “to ride/operate” vehicles in general (cars, motorbikes, horses). Use mengendarai motor (motorbike). Indonesians rarely say mengemudi motor.

Is belajar untuk mengemudi acceptable?

It’s not wrong, but natives usually prefer belajar mengemudi. Use belajar untuk when introducing a purpose or a noun:

belajar untuk ujian (study for an exam)
belajar untuk bisa mengemudi (study in order to be able to drive)

How would I say it informally?

Aku lagi belajar nyetir (mobil).
In Jakarta slang: Gue lagi belajar nyetir.
Match pronoun and style: saya/sedang (neutral–formal), aku/gue + lagi/nyetir (casual).

How do I negate it?

Several natural options:

General negation: Saya tidak belajar mengemudi (mobil).
Negating the ongoing aspect: Saya tidak sedang belajar mengemudi (mobil).
Casual with lagi: Saya lagi nggak belajar nyetir. / Saya nggak lagi belajar nyetir.
All are understood; choose based on formality and what you want to emphasize.

Can I say kursus instead of belajar?

Yes, if you mean you’re taking lessons:

Saya sedang ikut kursus mengemudi. (I’m taking a driving course.)
Colloquial: Saya lagi les nyetir.

How do I specify whose or which car?

Add a modifier:

Ownership: mobil saya/kamu/dia; or mobilnya (his/her/their/that car, depending on context).
Specificity: mobil itu (that car), mobil merah (the red car).
Example: Saya sedang belajar mengemudikan mobil teman saya.

Any register pitfalls I should avoid?

Don’t use memandu for “drive” in Indonesian (that’s Malay usage). In Indonesian, memandu = “to guide/lead (a tour).”
kereta means “train” in Indonesian; “car” is mobil (Malay uses kereta for “car”).

Is sedang redundant with sekarang?

You can use either; both together are fine but can sound a bit heavy:

Saya sedang belajar…
Sekarang saya belajar…
Saya sedang belajar… sekarang (acceptable, more emphatic/redundant).

Pronunciation tips for this sentence?

belajar: be-LA-jar (r is tapped; j like English “j”).
mengemudi: məng-ə-MU-di (the prefix meng- has a nasal “ng”).
mobil: MO-bil (like “mobile” without the final e).
Stress is light and often near the end; keep vowels pure and short.