A block copolyester comprises a hard segment and a soft segment, wherein the melting point of the copolyester is greater than or equal to 200° C., and the glass transition temperature of the copolyester is less than or equal to −40° C. The hard segment is preferably polyethylene terephthalate, polybutylene terephthalate, or polyethylene naphthalate. The soft segment is preferably formed from at least one dimer fatty acid and/or dimer fatty diol and/or equivalent thereof. The copolyester is especially suitable for use in automotive parts, particularly where thermal stability is required.