Tokom probne vožnje vozilo je brzo ubrzalo.

Tokom means during.

It is a preposition used with the genitive case, so the noun phrase after it changes form:

• probna vožnja = a test drive
• tokom probne vožnje = during the test drive

A very similar alternative is za vreme + genitive, but tokom is very common and slightly more formal in tone.

Because tokom requires the genitive case.

The base form is:

• probna vožnja = test drive

After tokom, both words go into genitive singular:

• probna → probne
• vožnja → vožnje

So:

• tokom probne vožnje = during the test drive

Probna vožnja literally means trial drive or test drive.

• proban / probna / probno relates to testing or trial
• vožnja means driving, ride, or drive

In everyday English, the best translation is usually test drive.

Vozilo means vehicle, so it is a more general word than auto or automobil.

• vozilo = vehicle
• automobil / auto = car

So this sentence says the vehicle accelerated quickly, not necessarily the car accelerated quickly. It sounds a bit more neutral or technical.

Je is the 3rd person singular present form of biti (to be) and is used as an auxiliary verb to form the perfect tense in Serbian.

So the past tense here is built like this:

• je
  • ubrzalo

Together:

• vozilo je ubrzalo = the vehicle accelerated

This is the normal way to form many past-tense sentences in Serbian.

Because ubrzalo agrees with vozilo, which is a neuter singular noun.

In Serbian past tense, the participle agrees in gender and number with the subject:

• masculine singular: ubrzao
• feminine singular: ubrzala
• neuter singular: ubrzalo

Since vozilo is neuter:

• vozilo je ubrzalo

The verb is ubrzati (ubrzati se / ubrzavati), and here ubrzalo means accelerated or sped up.

In this sentence:

• ubrzalo = accelerated

It refers to the vehicle increasing speed.

Ubrzati is perfective.

That matters because perfective verbs usually present an action as a completed whole or a single event. Here, the idea is that the vehicle did accelerate / sped up, seen as a complete occurrence during the test drive.

Its imperfective partner is usually:

• ubrzavati = to be accelerating / to accelerate repeatedly or in progress

So compare:

• Vozilo je ubrzalo. = The vehicle accelerated.
• Vozilo je ubrzavalo. = The vehicle was accelerating / kept accelerating.

Brzo is an adverb meaning quickly or fast.

It modifies the verb ubrzalo:

• brzo ubrzalo = accelerated quickly

This may sound a little repetitive in English because accelerate already implies becoming faster, but it is perfectly natural in Serbian. It emphasizes that the acceleration happened rapidly.

This is normal Serbian word order, especially because je is a clitic.

Clitics in Serbian usually come in the second position of the clause. That is why je appears after the first phrase or word of the main clause:

• Vozilo je brzo ubrzalo.

You could change the word order for emphasis, but the clitic still tends to stay near the beginning:

• Tokom probne vožnje je vozilo brzo ubrzalo. — possible, but less natural here
• Vozilo je ubrzalo brzo. — possible, but less neutral

The given sentence is the most natural neutral order.

Because Serbian has no articles like English a/an/the.

So:

• vozilo can mean a vehicle or the vehicle
• probna vožnja can mean a test drive or the test drive

The exact meaning depends on context. In this sentence, English naturally uses the test drive and the vehicle, but Serbian does not need separate article words.

A simple pronunciation guide is:

Tokom probne vožnje vozilo je brzo ubrzalo.
TOH-kom PROB-neh VOZH-nyeh VOH-zee-lo yeh BR-zoh oo-BR-zah-loh

A few useful notes:

• ž sounds like the s in measure
• nj sounds like the ny in canyon
• j is like English y in yes

So vožnje is roughly VOZH-nyeh.

Yes, you could.

These are close in meaning:

• tokom probne vožnje = during the test drive
• u toku probne vožnje = in the course of / during the test drive

Tokom is shorter and very common.
U toku can sound a bit more formal or administrative in some contexts, but both are correct here.

Yes. It is in the perfect tense, which is the most common Serbian past tense in everyday language.

The structure is:

• auxiliary biti in the present: je
• past participle: ubrzalo

So:

• vozilo je ubrzalo = the vehicle accelerated / has accelerated

In most everyday contexts, this is simply understood as a normal past action.