2006 Lexus RX 400h Road Test

A peculiar aspect of the 400h's full-time all-wheel drive setup is the absence of a driveshaft connecting the front wheels to the

A peculiar aspect of the 400h's full-time all-wheel drive setup is the absence of a driveshaft connecting the front wheels to the rear wheels by way of a transfer case. (Photo: Rob Rothwell, Canadian Auto Press)

rear wheels by way of a transfer case. Instead, the rear wheels are powered strictly by the electrical side of the hybrid house, with the use of an electric motor/generator configuration set mid-point in the rear axle. As with most modern all-wheel drive formats, the RX 400h will direct power to the wheel(s) that have grip when the going gets icy. When icy turns to dicey, the RX's Vehicle Dynamics Integrated Management (VDIM) system will intercede with brake management to assist in restoring driver control.

Conventional gasoline-powered vehicles achieve a pathetic level of efficiency in terms of energy produced and wasted. As I recall, the typical gas-powered vehicle achieves an energy

The typical gas-powered vehicle achieves an energy efficiency of roughly 14 per cent. Lexus has taken every step possible to improve upon that. (Photo: Rob Rothwell, Canadian Auto Press)

efficiency of roughly 14 per cent. Lexus has taken every step possible to improve upon that. For example, in the RX 400h, the power steering mechanism and air conditioning apparatus are electronic, rather than engine driven. This reduces the amount of lost energy at the crankshaft.

When it comes to the judicious use of electrical power, the 400h conserves all it can, its LED tail and brake lights being but one example. And thanks to its all-wheel drive configuration, regenerative braking from all four wheels kicks a healthy dose of recharge back to the wafer-thin hybrid battery pack, which resides on the floor under the back seat.