TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Composition: The fuel composition further comprises cetane improver, non-metallic combustion modifier, metallic combustion modifier, water-soluble salt, antiknock agent, lead scavenger, ashless dispersant, deposit preventer or modifier, dye, antioxidant, rust inhibitor, corrosion inhibitor, bacteriostatic agent, gum inhibitor, metal deactivator, upper cylinder lubricant, antifreeze agent, biocide, organic solvent or their mixture, and carboxylic acid, succinic acid, formic acid, acetylene dicarboxylic acid, benzene hexacarboxylic acid, benzene pentacarboxylic acid, benzene tetracarboxylic acid, benzene tricarboxylic acid, 2-butyl-l,4-dioic acid, 2-butynoic acid, citraconic acid, cyclopropane-1,1-dicarboxylic acid, 2,6-dihydroxy benzoic acid, dihydroxy maleic acid, dihydroxy malic acid, dihydroxy tatric acid, alpha, alpha-dimethyloxaloacetic acid, dipropylmalonic acid, ethylene oxide dicarboxylic acid, hydroxy aspartic acid, maleic acid, 2-oxobutanoic acid, triethyl succinic acid, citric acid, tartaric acid, glyoxalic acid, oxalic acid, lactic acid, oxomalonic acid or their mixture. Alternately, the water blended fuel composition contains liquid hydrocarbon fuel, water, acid having pKa of 1.5-6, polyisobutylene-substituted succinic acid having polyisobutylene group with number average molecular weight of 750-3000, and alkoxy polyethoxy alcohol having alkoxy group containing 9-11 carbon atoms, preferably 14-30 carbon atoms and polyethoxy group containing 8 ethoxy groups, preferably up to 10 ethoxy groups.Preferred Components: The liquid hydrocarbon fuel comprises petroleum distillate fuel such as diesel fuel, gasoline, fuel oil or their mixtures, alcohol, ether, ethanol, fuel derived from vegetable source, biodegradable fuel, biodiesel fuel, fluid derived from mineral source, residual fuel, bitumen, liquid fuel derived from corn, alfalfa, rapeseed, soybeans, shale, coal or their mixture, fuel derived from Fischer-Tropsch synthesized hydrocarbon, or their mixture. The nitrogen-free surfactant (a) comprises polyisobutylene substituted succinic acid or reaction product or reactive equivalent of polyisobutylene substituted succinic acid with an alcohol. The surfactant of formula (I) is 9-11C alkoxy poly(ethoxy)8 alcohol, 12-15C alkoxy poly (isopropoxy)22-26 alcohol, oleyl alcohol pentaethoxylate or their mixture. The surfactant of formula (II) is diglycerol monooleate, diglycerol monostearate, polyglycerol monooleate or their mixture. The surfactant of formula (III) is polyethylene glycol distearate, polyethylene glycol dioleate, polyethylene glycol soya bean oil ester or their mixture. The surfactant of formula (IV) is glycerol monooleate, diglycerol dioleate, diglycerol distearate, polyglycerol dioleate or their mixture. The surfactant of formula (V) is sorbitan monooleate, sorbitan monoisostearate, sorbitan sesquioleate, sorbitan trioleate or their mixture. The surfactant of formula (VI) is polyethoxy glycerol tri-oleate. The acid having pKa of 1.5-6, comprises tartaric acid.    TECHNOLOGY FOCUS - POLYMERS - Preferred Component: The hydrocarbyl substituent for nitrogen-free surfactant (a) is derived from polyisobutylene, polypropylene, polyethylene, copolymer derived from isobutene and butadiene, or copolymer derived from isobutene and isoprene. Preferred Definitions:    R=6-30C hydrocarbyl, preferably 9-11C hydrocarbyl;    R'=2-4C alkylene, preferably 2C alkylene;    R"'=H; and    n=1-10, preferably 8.    EXAMPLE - Fuel oil (in wt.pts) (87.17), polyisobutene-substituted succinic anhydride (1.9) having number average molecular weight of 2300, alkoxy polyethoxylated alcohol (RO(CH2CH2O)8H, where R was 9-11C group) (0.52), tartaric acid (0.41) and distilled water (10), were blended with high shear mixer, to obtain water-in-oil emulsion type water blended fuel formulation. The formulation had continuous oil phase and discontinuous aqueous phase comprising aqueous droplets with mean diameter of 0.8 micron. The water blended fuel formulation had high combustion efficiency with reduced emission of nitrogen oxides.