customs

Which 5 countries? Are they all Schengen? Are you asking about Customs ( bringing in dutiable goods) or Immigration/Passport control?

There are no longer regular border passport checks within the Schengen zone. However, countries can and will resort to border checks in an emergency. There are no custom between European Union countries. So, between France and Schengen but non-EU Switzerland, you could have customs (usually a formality) but no passport control. However, between France and the UK (currently), you could have passport control but no customs. With Brexit, that could change.

I have the same questions as the first reply - which five countries are you driving through?

North Americans seem to confuse customs and immigration. They are two very different things.

• Customs is the check on goods. Checking the contents of your luggage to see if it contains any forbidden items or items for which customs duties (taxes) must be paid.
• Immigration (aka passport control) is the check on people. Checking whether you are allowed into the country and if so for how long. This is where your passport is stamped if necessary.

Customs is the one you need to worry about the least, as most people are not stopped, they just stop and check a small random sample.
The EU (European Union) is a customs union. You (or rather your luggage) DOES NOT go through customs when travelling between EU countries.
The Schengen Area is a passport union. You DO NOT go through immigration when travelling between Schengen Area countries.
If both countries are members of both the EU and the Schengen Area there are no border controls, you will (normally) not be stopped at their border.

Since some countries are members of one, the other or both; depending on which border you go through you may have to go through immigration, customs, or both or neither. To work out which, you need to say which countries you are travelling between.
Or look at this map: https://ec.europa.eu/home-affairs/sites/homeaffairs/files/schengen_map.jpg