<P> In December 2010, the 2011 Acura RL was announced with a second Mid Model Change, featuring, among other things, a six - speed automatic transmission . </P> <P> On November 30, 2011, as part of the publicity surrounding the 2011 Tokyo Auto Show, Honda announced a new implementation of SH - AWD as part of its "Earth Dreams Technology". The new hybrid electric SH - AWD would be based on an all new 3.5 L V - 6 and three electric motors and lithium - ion battery technology . The V - 6 would be mated to a 30 kW electric motor which could operate independently of the V - 6, unlike earlier mild hybrid Honda IMA configurations . In addition, each rear wheel would have a 20 kW electric motor that would operate independently, varying torque as conditions demand . On a turn, the electric motor would apply torque to the outside rear wheel, while the inside rear wheel motor would drag, amplifying the SH - AWD effect . At the same time, the dragging motor would act as a generator, feeding power to the outside wheel motor . If the lithium ion pack became depleted, the V - 6 would power the front electric motor as generator to feed electricity to rear wheels while also charging the battery . A prototype of this system was shown in a test mule using an 8th generation North American version of the Honda Accord . </P> <P> Current SH - AWD configurations are all mated to a transverse engine, either a turbo - charged in - line four - cylinder Honda K - Series engine in the case of the RDX, or naturally aspirated V - 6 versions of the Honda J - Series engine . The engines are mated to a front - wheel - drive transaxle . There is no center differential . The transaxle is bolted to torque transfer unit that spins a center drive shaft that powers the rear differential unit . The rear differential is a T - shaped device . Power coming from the engine is transferred via a central hypoid gear that delivers power to each rear axle . Power to the each axle is modulated by identical planetary gear sets and electromagnetic clutch packs which can vary incoming power side to side . </P> <P> As described earlier, SH - AWD can vary torque side to side through the rear wheels . This ability to drive one of the rear wheels with more power (remember the row boat analogy) is accomplished through overdriving the rear wheels with respect to the front wheels . The Acura RL is designed with a third planetary gear set and clutch pack that are packaged into a so - called "Acceleration Device", which is bolted in front of the rear differential unit . The Acceleration Device allows torque to be passed to the rear wheels at a near one to one ratio, but in cornering situations, the Acceleration Device variably increases the torque passed to the rear up to 5%, depending on the cornering situation . </P>

What does sh stand for on acura mdx