Learn Hardcore French: Ma voiture est en panne aujourd'hui.

panne on its own means a breakdown / a failure:
- une panne d’électricité = a power cut
- une panne de voiture = a car breakdown
The structure en + noun often expresses a state or condition:
- en vacances = on vacation
- en colère = angry
- en retard = late
- en forme = in good shape

So en panne literally suggests “in a state of breakdown,” but you should just remember it as the standard way to say out of order / broken down.

There is no article because en panne is a set phrase, just like en vacances, en prison, en colère. You do not say:

✗ Ma voiture est dans une panne
✗ Ma voiture est en une panne

The natural form is simply Ma voiture est en panne.

What is the difference between être en panne and tomber en panne?

être en panne = to be broken down, describing the current state:
- Ma voiture est en panne aujourd’hui.
  = My car is not working today.
tomber en panne = to break down, describing the moment when it stops working:
- Ma voiture est tombée en panne ce matin.
  = My car broke down this morning.

So:

Use être en panne for the situation now or at a given time.
Use tomber en panne for the event of breaking down.

Could I say Ma voiture est cassée or Ma voiture a cassé instead of Ma voiture est en panne?

Sometimes, but the meaning changes.

Ma voiture est en panne
→ The car has a mechanical / technical problem and doesn’t work.
Ma voiture est cassée
→ The car is broken / damaged, usually physically (after a crash, something is broken on it).
It sounds more like the car is wrecked or broken as an object, not just temporarily out of order.
Ma voiture a cassé sounds wrong in standard French.
casser is mainly transitive:
- J’ai cassé ma voiture. = I broke my car.
  Or sometimes reflexive for objects:
- La vitre s’est cassée. = The window broke.

For a car that just won’t start or has a mechanical failure, the natural choices are:

Ma voiture est en panne.
Ma voiture ne marche pas. (less specific, just “my car doesn’t work.”)
Ma voiture est tombée en panne. (for the moment it broke down).

Why is it ma voiture and not mon voiture?

Because voiture is feminine singular, and French possessive adjectives agree with the gender and number of the noun possessed, not with the person who owns it.

For je (I), the forms are:

mon = my (masculine singular, or feminine before a vowel sound)
ma = my (feminine singular)
mes = my (plural, masculine or feminine)

Since voiture is feminine singular and starts with a consonant:

ma voiture = my car

Other examples:

mon frère = my brother (masc. sing.)
ma sœur = my sister (fem. sing.)
mes parents = my parents (plural)

Note that for feminine nouns starting with a vowel or silent h, French uses mon for pronunciation reasons:

mon amie (not ma amie)
mon habitude

But voiture begins with v, so you must say ma voiture, never mon voiture.

Why is voiture feminine? Is there a rule?

There is no reliable rule that lets you guess the gender of every noun. In French, nouns are grammatically masculine or feminine, and you generally have to learn the gender with the word.

la voiture (feminine) = the car
Dictionaries will often mark it as n. f. (nom féminin).

Some patterns exist (for example, many nouns ending in -tion are feminine), but they have many exceptions.

For vehicles:

Feminine: la voiture, la moto, la bicyclette
Masculine: le train, le bus, le vélo

So you just need to memorize la voiture, and then you know to use ma voiture, une voiture, cette voiture, etc.

Can aujourd’hui go at the beginning of the sentence, like Today my car is broken down?

Yes. Both word orders are correct:

Ma voiture est en panne aujourd’hui.
Aujourd’hui, ma voiture est en panne.

Putting aujourd’hui at the beginning slightly emphasizes the time (today), but both sentences mean the same thing and are very natural.

What is not natural in standard French is:

✗ Ma voiture aujourd’hui est en panne. (sounds awkward unless used deliberately for special emphasis or style)

How do you pronounce aujourd’hui and en panne?

Approximate them with English sounds:

en panne → [ɑ̃ pan]
- en: nasal sound like “ahn” (do not pronounce a clear n at the end).
- panne: like “pan” with a short a (closer to the a in “father”), and you do pronounce the n.
aujourd’hui → [oʒuʁdɥi]
Roughly: “oh-zhoor-dwee”
- au: “oh”
- jour: “zhoor” (like the s in “measure”
  - “oor”)
- d’hui: “dwee” (the h is silent, and ui is like “wee” but with the lips very rounded)

Spoken smoothly, Ma voiture est en panne aujourd’hui sounds a bit like:
Ma vua-tur ê-tan pan no-zhoor-dwee.

Why is aujourd’hui written as one word with an apostrophe?

Historically, aujourd’hui came from a longer expression meaning “on the day of today” (au jour de hui).

Over time, it fused into the single modern word aujourd’hui:

One word
One apostrophe
No spaces: aujourd’hui, not ✗ aujourd hui or ✗ aujour d’hui

So the correct sentence is:

Ma voiture est en panne aujourd’hui.

Why do we need est in the sentence? Could we just say Ma voiture en panne aujourd’hui?

In a normal full sentence, French requires a verb, and for this kind of structure you must use être:

Ma voiture est en panne aujourd’hui. ✔

Without est, Ma voiture en panne aujourd’hui is not a complete sentence; it is just a noun phrase plus a phrase describing it.

Compare:

La voiture est rouge. = The car is red. (full sentence)
La voiture rouge = the red car (just a noun phrase)

Similarly, you could use ma voiture en panne only as part of a larger sentence:

Ma voiture en panne est devant la maison.
= My broken-down car is in front of the house.

But when it is the main statement, you need est:

Ma voiture est en panne aujourd’hui.

How would I say the same idea in the past or future?

You keep the same structure and change the tense of être or use tomber en panne for the breakdown event.

Past state (was broken down yesterday):
- Ma voiture était en panne hier.
  = My car was broken down yesterday.
Past event (broke down this morning):
- Ma voiture est tombée en panne ce matin.
  = My car broke down this morning.
Present state continuing since a point in time:
- Ma voiture est en panne depuis lundi.
  = My car has been broken down since Monday.
Future state (will still be broken down tomorrow):
- Demain, ma voiture sera encore en panne.
  = Tomorrow, my car will still be broken down.