רכיבת המבחן עוזרת לנו להתמקח.

Because רכיבת is the construct form (called סמיכות) of רכיבה.

• רכיבה = riding / a ride
• רכיבת ... = ride of ... / riding of ...

So:

• רכיבת מבחן = a test ride
• רכיבת המבחן = the test ride

This is a very common Hebrew pattern with noun-noun combinations.

In a construct chain, definiteness is usually marked on the second noun, but it makes the whole phrase definite.

So:

• רכיבת מבחן = a test ride
• רכיבת המבחן = the test ride

This is different from English, where the usually goes before the whole phrase. In Hebrew, the definiteness often shows up only on the last word of the construct phrase.

That is a normal change when certain feminine nouns go into the construct form.

A noun ending in ־ה often changes to ־ת in construct:

• רכיבה → רכיבת
• מכונית does not change the same way because it already has a different feminine ending
• another common example: שנה → שנת

So רכיבת המבחן is not a different word you just memorize separately; it is the construct form of רכיבה.

Because the subject, רכיבת המבחן, is grammatically feminine singular.

The core noun is רכיבה, which is feminine. Therefore the verb must agree with it:

• רכיבת המבחן עוזרת = feminine singular
• if the subject were masculine singular, you would expect עוזר
• if it were feminine plural, you would expect עוזרות

So the verb form is agreeing with רכיבת.

לנו means to us or for us, depending on the context.

It is made from:

• ל־ = to / for
• נו = us

With the verb לעזור (to help), Hebrew usually uses ל for the person being helped:

• הוא עוזר לי = he helps me
• היא עוזרת לנו = she helps us
• רכיבת המבחן עוזרת לנו = the test ride helps us

So Hebrew says something more like helps to us, even though in natural English we just say helps us.

Because after עוזר / עוזרת, Hebrew often uses an infinitive to say helps someone do something.

Pattern:

• X עוזר ל־Y + infinitive

For example:

• זה עוזר לי להבין = this helps me understand
• התרגול עוזר להם לזכור = the practice helps them remember
• רכיבת המבחן עוזרת לנו להתמקח = the test ride helps us haggle

So להתמקח is simply the action that the test ride helps us do.

Hebrew infinitives normally begin with ל־.

So:

• להבין = to understand
• לזכור = to remember
• להתמקח = to haggle / to bargain

That ל־ is just part of the infinitive form. It does not mean a separate to in the sense of direction here.

להתמקח is a verb in the התפעל pattern.

A few useful things about that:

• Many התפעל verbs begin with הת־ in the past or infinitive.
• The infinitive often looks like להת...
• The present-tense form would be מתמקח (masculine singular) or מתמקחת (feminine singular)

So you may see:

• אני מתמקח = I haggle
• היא מתמקחת = she haggles
• להתמקח = to haggle

You do not need to read a deep reflexive meaning into it every time; here it just means to bargain / haggle.

Usually it suggests bargaining or haggling, especially over a price or deal.

So it is more specific than a broad verb like לנהל משא ומתן (to negotiate). In many everyday buying situations, להתמקח is the natural choice if you mean trying to get a better price.

In this sentence, the idea is that the test ride gives you leverage when discussing the price.

It is natural if the thing is something you ride, such as a bicycle, motorcycle, or possibly a horse depending on context.

For a car, Hebrew more often uses:

• נסיעת מבחן = test drive

So the choice of רכיבת suggests something that is ridden rather than driven.

Yes, Hebrew word order is somewhat flexible, although the given sentence is perfectly normal.

For example, לנו could sometimes move for emphasis:

• רכיבת המבחן עוזרת לנו להתמקח = neutral, standard
• רכיבת המבחן עוזרת להתמקח = possible, but now us is omitted
• לנו רכיבת המבחן עוזרת להתמקח = marked/emphatic, not the most neutral order

For learners, the original order is the safest and most natural one to use.

A simple pronunciation guide is:

rekhivat ha-mivkhan ozeret lanu lehitmakeaḥ

A few notes:

• רכיבת = rekhivat
• המבחן = ha-mivkhan
• עוזרת = ozeret
• להתמקח = lehitmakeaḥ

The ח sound is the throaty sound heard in many Hebrew words, not an English h.