The consumption of fossil fuels is one of the largest problems facing humankind. One of the heaviest users of our non-renewable resources is the automotive industry, in particular, the heavy road transport sector. Tightening worldwide legislation aims to place restrictions on the heavy transport industry to reduce its use of fossil fuels and reduce the levels of pollution being released to the atmosphere. Although several different alternatives to the conventional Internal Combustion Engine (ICE) have been investigated, none have as yet become a competitive source of energy. Alternative research into development of hybrid-drive vehicles was specifically concerned with electric hybrids especially for passenger vehicles. Currently there is a resurgence of interest in the Hydraulic-type Hybrid Vehicle (HHV) in application to commercial and to a lesser degree to large passenger vehicles. This paper gives an overview of hydraulic hybrid technology.