Distilation profile is a description of how much of a hydrocarbon mixture vaporizes at different temperatures.

Gasoline is a complex mixture of different hydrocarbons with different properties. Consequently, when heated, different components will vaporize at different temperatures. How much gasoline vaporizes at low temperatures (front end volatility), medium temperatures (mid-range volatility) and high temperatures (tail-end volatility) will effect performance across wide range of dimensions and is known as the distillation profile of the fuel. 

 The performance effected includes:

Front-end volatility (low temperatures):

Cold start

Hot start

Avoiding vapor lock

Minimizing evaporative emissions

Mid-range volatility (medium temperatures):

Achieving quick warm up

Fuel efficiency on short trips

Good power and acceleration

Avoiding carburetor icing

Avoiding hot stalling

Tail-end volatility (High temperatures):

Fuel efficiency after warm up

Avoiding engine deposits

Minimizing dilution of crankcase oil

Minimizing VOC emissions

Distillation properties are typically measured as the temperatures of initial boiling, at specific volume percent recovery (5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95%), and end point or final volume recovery.