Translation:The Mexican car is moving alongside the German one.
"Személy" is more impersonal, more neutral, a bit official. You could hear it in the news, or when just talking about the number of people somewhere. "Ember" is more human. Sometimes "ember" is understood to be a man, but it can be used for any gender. And, for example, when you say "she is a good person", Hungarian would say "Ő egy jó ember".
Various derived words exist, just like in English:
personal - személyes, személyi
personality - személyiség
personnel - személyzet
humane - emberséges, emberies
humanity - emberiség
human - ember, emberi
humanitarian - humanitárius
There is another word for people:
individual - egyén
The verb "to travel" works here. A car can travel along a vector, which can be beside the vector of another car. See definition two - "To pass from here to there; to move or transmit; to go from one place to another." Example: "Soundwaves can travel through water." (https://en.wiktionary.org/wiki/travel#Verb)
Recommended translation: "The Mexican car travels beside the German one."
The thing is, one is not passing the other. They are moving at the same speed. Most likely. Or at least that is how it looks like at the moment. They are moving side by side.
If it were a passing situation, then we could use "elhalad a német mellett". If it is a definite overtaking, then we can use "(meg)előzi a németet".