Learn Hardcore Japanese: watasi ha kuruma de byouin ni ikimasu.

は is the topic marker, introducing "私" (I) as the topic of the sentence: “As for me...” が is the subject marker, often used to present new information or emphasize the doer of an action. Here, we’re not emphasizing “who” but simply stating “as for me, I go...” so は is appropriate.

Why is the particle は pronounced wa here and not ha?

When used as a particle, は is always pronounced wa. The spelling is historical. When は is part of a regular word (not a particle), it’s pronounced ha.

What does 車で mean? Why is で used after 車?

で marks the means or instrument used to do something. 車で literally means “by car” or “using a car.” It tells us how the action is carried out.

Why don’t we use に or を with 車 here?

を would make 車 the direct object (e.g. “I wash the car”), which doesn’t fit “go by car.”
に after 車 would usually mark a location or destination (e.g. 車に乗る “get on the car”). To express “by car” you need the instrumental で.

Why is 病院 followed by に? What role does に play?

に marks the destination or goal of motion. 病院に行きます means “go to the hospital.” Without に, the verb wouldn’t know where you’re going.

Could I replace に with へ after 病院? What’s the nuance difference?

Yes, you can say 病院へ行きます. Both に and へ mark direction, but:

に focuses on arriving at a specific place.
へ emphasizes direction toward that place, a bit more vague about arrival.

What is 行きます? How do I form other tenses or the dictionary form?

行きます is the polite present/future tense of 行く (“to go”).

Dictionary (plain) form: 行く
Polite past: 行きました (“went”)
Polite negative: 行きません (“do not go”)
Plain past: 行った
Plain negative: 行かない

Why is the verb 行きます at the end of the sentence? Is that always the pattern in Japanese?

Japanese is generally Subject–Object–Verb (SOV). Modifiers and particles come before the verb, and the verb naturally appears at the end. While you can rearrange some elements for emphasis, the verb typically closes the clause.

Can we drop 私 and just say 車で病院に行きます? Would it still be clear?

Yes. In Japanese, subjects or topics like 私 are often omitted if they’re clear from context. 車で病院に行きます still means “(I) go to the hospital by car,” assuming you’re talking about yourself.

How can I make this sentence more casual or informal?

Switch to the plain form and optionally drop particles in very casual speech:

Plain polite: 私は車で病院に行く。
Omit topic: 車で病院に行く。
Very casual (dropping a particle): 車で病院行く。
Be careful: dropping particles can sound abrupt or rough, so use it only in informal settings.