Horse outward similarity is an unreliable measure of relatedness. Besides the horse, there are six other species of genus "Equus" in the Equidae family. These are the ass or donkey, "Equus asinus"; the mountain zebra, "Equus zebra"; plains zebra, "Equus quagga"; Grévy's zebra, "Equus grevyi"; the kiang, "Equus kiang"; and the onager, "Equus hemionus". Horses can crossbreed with other members of their genus. The most common hybrid is the mule, a cross between a "jack" (male donkey) and a mare. A related hybrid, a hinny, is a cross between a stallion and a jenny (female donkey). Other hybrids include the zorse,
Hyundai Equus only Tau 4.6 MPi for the 2011 model (390PS) engine. The Tau 5.0 GDi was from 2012 forward. All models included ZF 6-speed automatic transmission with SHIFTRONIC manual control. 2012 model vehicles include 8-speed automatic transmission, introduction of GDI engines. It was also revealed that the Hyundai Equus will be receiving a 5.0L V8 with and . This engine will be an option for the Equus after January 2011. This engine will also be placed in the facelifted 2012 Hyundai Genesis. Korean models went on sale in 2012. It is a limited (3 units) version of 2013 Hyundai Equus limousine