Firstly, there are 18 different isomers of octane, each having a unique boiling point.

The gasoline standard is that "100 octane" corresponds to pure iso-octane (2,2,4-trimethylpentane).

Iso-octane has a boiling point of 99°C.

Secondly, the mass rate of evaporation, according to the Hertz-Knudsen equation, given everything else is equal, is proportional to the square root of molecular weight. Therefore, if the vapor pressure of water and iso-octane are approximately the same, the mass-rate of evaporation of octane should be greater.

See also problem 1b here.

Firstly, there are 18 different isomers of octane, each having a unique boiling point.

The gasoline standard is that "100 octane" corresponds to pure iso-octane (2,2,4-trimethylpentane).

Iso-octane has a boiling point of 99°C.

Secondly, the mass-rate of evaporation, according to the Hertz-Knudsen equation, given everything else is equal, is proportional to the square root of molecular weight. Therefore, if the vapor pressure of water and iso-octane are approximately the same, the mass-rate of evaporation of octane should be greater.

See also problem 1b here.

Thirdly, since the density of octane is about 0.7 relative to water, if equal-volume drops are being evaporated, the rate of evaporation will be even greater than the mass-rate.