|Rx 400h in police livery.|
Testdriven. Lexus is kitting out the Rx 400h hybrid for police trials in the UK.
The acceptance of the hybrid into police trials highlights the increasing optimization of the hybrid platform for power. Although a number of cities in the US, for example, are mandating some percentage of hybrid or alternative fuel vehicle purchases, most often those mandates exclude emergency response vehicles—e.g., the police—aside from administrative transport.
The RX 400h uses an enhanced version of the Hybrid Synergy Drive system that combines the 3.3-liter V6 gasoline engine with a high-torque electric drive motor-generator plus a rear electric drive motor-generator to provide on-road all-wheel drive (AWD) capability.
|The front power unit of the Rx 400h.|
A good deal of the performance of the vehicle is due to the design of its front power unit.
The Lexus hybrid uses a water/oil cooled, AC synchronous type motor of a high-efficiency DC, brushless design operating on AC current. A rotor constructed from stacked, electromagnetic steel plates and Neodymium permanent magnets arranged in a V configuration combine to maximize drive torque and power output.
This, combined with a boost in power supply voltage to 650V, a significant increase in motor rotation speed to a maximum of 12,400 rpm and the adoption of a planetary gear to amplify torque through motor speed reduction increases power output by approximately 2.48 times that of the Prius motor, despite the respective units being of near identical size.
The power output of 123 kW (167 hp) and 333 Nm of torque currently gives the power unit the highest output per unit of weight and volume in the world.
A rear-axle 650V electric motor that kicks in when the vehicle needs 4WD spins at up to 10,752 rpm and generates a maximum output of 50 kW (67 hp) and 130 Nm of torque.
The combined full hybrid system delivers 268 hp (200 kW). [Lexus initially published a figure for combined axle torque of 3,500 lb-ft. Likely a typo, although it has not published a combined system torque number since. Further discussion of the toque number is below in the comments section.]
The luxury hybrid accelerates from zero to 60 mph in 7.3 seconds—about 0.5 seconds quicker than the RX 330. (Earlier post.)
The Hampshire police will be the first force to test the hybrid SUV under full police specification and under police operational conditions. Initial trials in the Hampshire force went very well.
We have already received positive feedback from our officers after an initial trial and know that the vehicle’s performance was outstanding, with quick acceleration and more than adequate response throughout the range of the electronic gearbox. We eagerly await the fully equipped model when we will be able to put it through its paces and gauge the performance under police operational conditions.—John Bradley, Hampshire Police Fleet Manage