A key component of Need of Speed Unbound's gameplay is what is known as a Nitrous boost. Nitrous, simply put, are boosts that allow drivers to get speed boosts. Between jetting past opposing races or darting away from the cops, these Nitrous boosts will almost certainly come in handy throughout the story mode of Unbound. So, how can you do a Nitrous boost in Need for Speed Unbound? Let's take a look at what you will need to know. Related: Which starter junker should you choose in Need for Speed Unbound? How to activate Nitrous boost in Need for Speed Unbound Doing a Nitrous boost in Need for Speed Unbound is relatively simple. You will have to press and hold either A (for Xbox) or X (for PlayStation) to get that added boost in Lakeshore City. Drivers also have access to a much smaller Nitrous boost, which can be accessed by tapping either A or X. While that sounds simple, it's important to note that Nitrous boosts are temporary. This is because there is a meter that can be found at the bottom of the screen, right next to the speed and gear gauge. This meter indicates how much Nitrous fuel is available at a given time. Screenshot by Gamepur How to refill Nitrous fuel meter If you're looking to refill the meter, here's what you need to know. Jumps, near misses, drifts, and trading paint all help refuel the Nitrous meter. Attempting to do any of the following and succeeding will go a long way towards filling up the meter again and receiving some much-needed boosts for later on in races.