A thermoelectric power generation (TEG) unit configured to be integrated into the exhaust system of a vehicle includes a plurality of thermoelectric power generator modules, each comprising an electrically interconnected plurality of p-type and n-type thermoelectric material legs, each leg extending between a substrate on a hot side and a substrate on a cold side of the module, wherein the thermoelectric materials for the legs are half-Heusler compounds having a thermoelectric figure of merit (ZT) greater than 1.0.