• If you use a lower octane than required, performance will suffer.
• If you use a higher octane than required, you will receive no benefit.

Volatility

Volatility is the measure of a gasoline's ability to vaporize.  This is important because it is a fuel/air mixture, and not liquid gasoline, that is burned in an engine.  If a gasoline is too volatile, the engine will stall.  If it is not volatile enough, it will cause hard starting and slow engine warm-up.

Velocity claims to have enhanced vaporization so that it can burn more easily.  If you've been having difficulty starting your engine when its cold, but experience no problems when starting a warm engine, then it may be due to insufficient volatility.  Velocity might help in this case.

However if your engine tends to stall in hot weather, or continues to turn a few seconds even after you've switched it off, then the higher volatility of this new fuel might not be for you.

Detergents

As the name suggests, detergents help clean an engine's fuel system and combustion chamber.  They are generally beneficial, but too much of them can be detrimental.  After all they do not perform a gasoline's primary function, which is to detonate at the right time and in the right way.

We asked Pilipinas Shell what exactly is in their additive or detergent package but since this is proprietary technology, they declined to reveal this at this time. 
With more detergents than is contained in Shell's normal unleaded gasoline, Velocity reportedly reduces carbon deposits in the fuel system (carburetor or EFI), combustion chamber, intake valves, and intake port area.  With reduced deposits, engines do start more easily, and run smoother and more economically.