Nitro efficiency index (Asphalt 8)


 * Nitro type definitions
 * Level 1 = Basic level of nitro, and the longest-lasting.
 * Level 2 = Triggered by firing nitro outside of the red zone . Equivalent to Perfect Nitro in terms of nitro efficiency.
 * Level 3 = Triggered by firing nitro again after triggering Level 2 nitro. Highest power, but the nitro gauge drains the fastest with this nitro level.
 * Perfect Nitro = Equivalent to Level 2 nitro in terms of nitro efficiency, except it has Level 3 power nitro. Triggered by firing the nitro once it hits the red zone (must be timed right).

For the nitro efficiency number definitions, numbers closer to zero denote longer-lasting nitro.


 * Nitro efficiency number definitions (Level 1)
 * 10: Very low
 * 9: Low
 * 8: Medium
 * 7: High
 * 6: Very high
 * 0~5: Extreme


 * Nitro efficiency number definitions (Level 2 / Perfect Nitro)
 * 15: Very low
 * 14: Low
 * 13: Medium
 * 12: High
 * 11: Very high
 * 0~10: Extreme


 * Nitro efficiency number definitions (Level 3)
 * 20: Very low
 * 19: Low
 * 18: Medium
 * 17: High
 * 16: Very high
 * 0~15: Extreme