Kvůli lijáku necháme podsedáky v autě.

Kvůli means because of here.

A very important grammar point is that kvůli takes the dative case. So the noun after it cannot stay in its basic dictionary form.

• kvůli lijáku = because of the downpour
• not kvůli liják

It can also mean for the sake of, depending on context, but in this sentence it clearly means because of.

Because liják has to be in the dative singular after kvůli.

The dictionary form is:

• liják = downpour

After kvůli, it changes to:

• lijáku = to/for/because of the downpour

So this is just a case ending:

• nominative: liják
• dative: lijáku

Necháme is the 1st person plural form of nechat.

It literally looks like a present-tense form, but nechat is a perfective verb. In Czech, the present forms of perfective verbs usually express future meaning.

So:

• necháme = we will leave
• not usually we leave in a general habitual sense

This is very common in Czech:

• udělám = I will do
• řekneme = we will say
• necháme = we will leave / let

The verb nechat can mean several things, including:

• leave
• let / allow
• sometimes have something done

In this sentence, leave is the natural meaning because of the structure:

• necháme podsedáky v autě

That pattern is:

• verb + object + place

So it means we’ll leave the booster seats in the car.

If it meant let, you would often see a different structure, for example:

• Necháme děti spát. = We’ll let the children sleep.

There, nechat is followed by a person/object plus an infinitive.

Czech often leaves out subject pronouns when they are not needed.

The ending -me in necháme already tells you the subject is we.

So:

• necháme = we will leave

You could say my necháme, but that would usually add emphasis, something like:

• We will leave them...

In normal neutral Czech, the pronoun is usually omitted.

Podsedáky is the accusative plural form, because it is the direct object of necháme.

The basic singular form is:

• podsedák

Plural:

• nominative plural: podsedáky
• accusative plural: podsedáky

For many masculine inanimate nouns, the accusative plural looks the same as the nominative plural.

So here:

• necháme co? = what will we leave?
• podsedáky

That is why the accusative is used.

Because the preposition v meaning in takes the locative case when it describes location.

So:

• auto = car
• v autě = in the car

This is a very common pattern:

• v domě = in the house
• v parku = in the park
• v autě = in the car

If you were talking about motion into the car, Czech would usually use a different preposition:

• do auta = into the car

So:

• v autě = location
• do auta = direction

Yes, you could also say that. Czech word order is fairly flexible.

Both are grammatical:

• Kvůli lijáku necháme podsedáky v autě.
• Necháme podsedáky v autě kvůli lijáku.

The difference is mainly about focus and information structure.

Starting with Kvůli lijáku puts the reason first, which can sound natural if:

• the rain is already the topic
• you want to emphasize the cause
• you are explaining a decision

So the original sentence feels a bit like:

• Because of the downpour, we’ll leave the booster seats in the car.

They can all relate to cause, but they work differently.

• kvůli + noun = because of
• protože + clause = because
• díky + noun = thanks to

Examples:

• Kvůli lijáku necháme podsedáky v autě.
  = Because of the downpour, we’ll leave the booster seats in the car.

• Necháme podsedáky v autě, protože venku strašně leje.
  = We’ll leave the booster seats in the car because it’s pouring outside.

• Díky hezkému počasí půjdeme pěšky.
  = Thanks to the nice weather, we’ll go on foot.

A useful nuance:

• kvůli often suggests something inconvenient, negative, or problematic
• díky usually suggests something positive

So kvůli lijáku is very natural, because a downpour is an unpleasant cause.

Yes. The noun podsedák can refer to a seat pad / seat cushion in some contexts, not only a child’s booster seat.

So the exact translation depends on context.

In everyday family context, podsedáky often means booster seats or booster cushions for children. In another context, it could simply mean seat cushions.

That is a vocabulary issue rather than a grammar issue, but it is worth knowing because Czech words are often a bit broader than a single English translation.