A novel polyhydroxy oligomer crosslinkable with polyisocyanates to form a coating composition adapted for use as an automotive topcoat which upon curing forms a hard, glossy, durable coating with outstanding durability and excellent resistance to solvents and water. The coating composition comprises:(A) a polyhydroxy oligomer having a number average (M.sub.n) molecular weight of between about 250-2000 and being the reaction product of:(i) an ester having pendant hydroxyl and carboxyl functionality and being made by reacting(a) a C.sub.3 -C.sub.10 aliphatic branched diol, and(b) an alkyl hexahydrophthalic anhydride; and(ii) a C.sub.2 -C.sub.10 monomer, having reactive functionality capable of esterifying said carboxyl functionality of said ester;(B) a polyisocyanate crosslinking agent having two or more reactive isocyanate groups per molecule; and(C) 0-50 weight percent based on the total weight of (A), (B) and (C) of a hydroxy functional additive having a number average weight (M.sub.n) of between about 150-6000.