What is a "slipstream"?

[MAX O ABSOLUTO LOUCO HOMEM]

"win the race and stay in a slipstream for at least 15 s" Chapter 5, 3.
In Portuguese, they translated it to "vacuum". I have no idea what it is.

[Ffej24]

Follow behind a racer close enough to mirror their their trail is a sliip stream
Stay on an opponents racer rear

[MAX O ABSOLUTO LOUCO HOMEM]

Oprindeligt skrevet af Ffej24:

Follow behind a racer close enough to mirror their their trail is a sliip stream
Stay on an opponents racer rear

Thank you, sir!!