TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Composition: The fuel composition further comprises at least an additive such as dispersant, demulsifier, defoamer, lubricity additive, antioxidant, cetane number improver, detergent, dye, corrosion inhibitor and/or odorant.Preferred Components: The diesel fuel of mineral origin exhibits a boiling point of 120-450degreesC and kinematic viscosity of 1-5 mm2/second, at 40degreesC, according to ASTM D445. The biodiesel fuel comprises fatty acid ester, obtained from 1-4C-monoalcohol, preferably 35 wt.% of saturated fatty acid ester with at least 16 carbon atoms. The biodiesel fuel is obtained from palm oil or an animal tallow. The monoester is methylester. The amount of the diesel fuel of mineral origin, biodiesel fuel, polymer and additive is at least 80, preferably 20-97.95 wt.%, 2-79.95 wt.%, 0.1-1 wt.% or 0.05-5 wt.% and 0-60 wt.%, respectively. The amount of ethylene copolymer is 0.01-0.5, preferably 0.05 wt.%.    TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The polymer is polyalkyl(meth)acrylate, polyalkyl fumarate and/or polyalkyl maleate. The polymer has 0.5-60, preferably 0.1-30 wt.% of repeating units from an ester monomer having 16-40C or 1-5C, or at most 3 wt.% of repeating untie from monomer containing hydroxy group such as alcohol containing sulfur group (IV) of formula ((R11)(R12)C=C(R)-C(=O)-OR10) or an alkoxylated compound (V) of formula ((-CH(R13)-CH(R14)-O)n-R15). The polymer with the ester group is obtained by the polymerization of a monomer mixture comprising 0-40 wt.% of one or more ethylenically unsaturated ester compound (I) of formula ((R3)(R2)C=C(R)-C(=O)-OR1), 10-98 wt.% of one or more ethylenically unsaturated ester compound (II) of formula ((R6)(R5)C=C(R)-C(=O)-OR4), 0.1-80 wt.% one or more ethylenically unsaturated ester compound (III) of formula ((R8)(R9)C=C(R)-C(=O)-OR7). The molecular weight of the polymer is 40000-600000 g/mol. The polymer exhibits a polydispersity index of 1-10, and thickening effect TE100, of 7.5-29 mm2/second, measured at 100degreesC.R = H or CH3;R1 = 1-6C-alkyl;R2 and R3 = H or -COORa;Ra = H or 1-6C-alkyl;R4 = 7-15C-alkyl;R5 and R6 = H or -COORb;Rb = H or 7-15C-alkyl;R7 = 16-40C-alkyl;R8 and R9 = H or -COORc;Rc = H or 16-40C-alkyll;R10 = 2-20C-alkyl with OH;R13-R14 = H or CH3;R15 = H or 1-20C-alkyl;n = 1-30;R11 and R12 = H or COORd; andRd = H, 2-20C-alkyl with an OH group or (V).