2006 Lexus RX 400h Long-Term Road Test


2006 Lexus RX400h: Engine braking optional

June 04, 2007

Cars without engine braking bug me. As a result I spend much of my commute all balled up. You see, the majority of the non-shifting masses here in L.A. don't think twice about slapping down the brake pedal in 70-mph traffic. Why?

Because they often have no choice. Give the wildly erratic traffic It takes much planning ahead to keep your automatic-transmission-equipped rig in a position where you never need to touch the brake pedal. And planning ahead in fast-moving traffic is something left to those of us who think about these things.

With engine braking planning ahead is less of a challenge. Lift off the throttle and the car slows down. Manual transmissions -- which lock the drive wheels to the engine do this any time the throttle is closed. It's one of the many physics-related reasons I'm convinced manual transmissions make people better drivers. This subtlety allows an attentive driver to efficiently pick a line through traffic without ever touching the brakes. Need to slow a little? Just back out of the gas. Automatics, however, slow very little when a driver lifts off the accelerator -- so down goes the brake pedal and on go the brake lights. The result is usually a crescendo of brake lights and unneeded slowing in the traffic behind.

I think I'm the only one who even thinks about this, so I'm going to throw it out there just for fun. What if, and believe me, this is a hypothetical, you could navigate a rapidly moving L.A. freeway without constantly working the brakes -- efficiently swapping lanes and even approaching a slower-moving car without braking? Would this not help flow? Would it not improve everyone's fuel economy? Would it not get us all home a little quicker?

I think so.

Getting to the point: I drove our RX400h home for the weekend. It has a continuously variable transmission, many of which suffer from the same off-throttle antics as automatic transmissions. Not this one. Just below Drive on the gear selector is a "B"for engine Braking. And it works. Score one for Lexus.

Josh Jacquot, Senior road test editor at 25,151 miles

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