Nitrous gives the Drifter Bike a short speed boost. Nitrous I costs 900 credits at Trust level 2. Use it to break away from a Horde or clear jumps, including some that lead to NERO research sites.
A burst of speed gets you away from a Horde that has closed in. It also clears gaps and ramps a normal run-up cannot.
You will need it for some NERO sites anyway, and it saves runs that go wrong.