An octane-enhancing additive includes a mixed butanol composition, sec-butyl ether, methanol, methyl tert-butyl ether, and a C4-dimer, the mixed butanol composition comprising sec-butanol and tert-butanol, and the C4-dimer comprising di-isobutylene, 2,2,4 trimethylpentane, 2,3,3 trimethylpentane, or a combination comprising at least one of the foregoing.

A fuel additive composition comprising an anthocyanidin; an amino acid; and a catalyst. The anthocyanidin may comprise delphinidin chloride. The amino acid may comprise aspartic acid, leucine acid, glutamic acid, a non-natural amino acid, or a combination thereof. Embodiments of the present invention also relate to a method for making of fuel additive, the method comprising: providing an anthocyanidin; contacting the anthocyanidin with an amino acid to form an anthocyanidin-amino acid mixture; contacting the anthocyanidin-amino acid mixture with a catalyst. The method may further comprise contacting the anthocyanidin-amino acid mixture with ethanol and/or an acid. The method may further comprise adjusting the pH of the anthocyanidin-amino acid mixture to less than 7.

An octane-enhancing additive includes a mixed butanol composition, sec-butyl ether, methanol, methyl tert-butyl ether, and a C4-dimer, the mixed butanol composition comprising sec-butanol and tert-butanol, and the C4-dimer comprising di-isobutylene, 2,2,4 trimethylpentane, 2,3,3 trimethylpentane, or a combination comprising at least one of the foregoing.

A fuel additive composition comprising an anthocyanidin; an amino acid; and a catalyst. The anthocyanidin may comprise delphinidin chloride. The amino acid may comprise aspartic acid, leucine acid, glutamic acid, a non-natural amino acid, or a combination thereof. Embodiments of the present invention also relate to a method for making of fuel additive, the method comprising: providing an anthocyanidin; contacting the anthocyanidin with an amino acid to form an anthocyanidin-amino acid mixture; contacting the anthocyanidin-amino acid mixture with a catalyst. The method may further comprise contacting the anthocyanidin-amino acid mixture with ethanol and/or an acid. The method may further comprise adjusting the pH of the anthocyanidin-amino acid mixture to less than 7.

A fuel additive composition comprising an anthocyanidin; an amino acid; and a catalyst. The anthocyanidin may comprise delphinidin chloride. The amino acid may comprise aspartic acid, leucine acid, glutamic acid, a non-natural amino acid, or a combination thereof. Embodiments of the present invention also relate to a method for making of fuel additive, the method comprising: providing an anthocyanidin; contacting the anthocyanidin with an amino acid to form an anthocyanidin-amino acid mixture; contacting the anthocyanidin-amino acid mixture with a catalyst. The method may further comprise contacting the anthocyanidin-amino acid mixture with ethanol and/or an acid. The method may further comprise adjusting the pH of the anthocyanidin-amino acid mixture to less than 7.

A fuel additive composition comprising an anthocyanidin; an amino acid; and a catalyst. The anthocyanidin may comprise delphinidin chloride. The amino acid may comprise aspartic acid, leucine acid, glutamic acid, a non-natural amino acid, or a combination thereof. Embodiments of the present invention also relate to a method for making of fuel additive, the method comprising: providing an anthocyanidin; contacting the anthocyanidin with an amino acid to form an anthocyanidin-amino acid mixture; contacting the anthocyanidin-amino acid mixture with a catalyst. The method may further comprise contacting the anthocyanidin-amino acid mixture with ethanol and/or an acid. The method may further comprise adjusting the pH of the anthocyanidin-amino acid mixture to less than 7.