Every good mark the RX line up earns in other areas is discredited by the hybrid's performance attributes. To get such excellent mileage, the V-6 engine is teamed with an electric motor and a large battery pack, along with regenerative brakes that send brake force to recharge the battery. This is one of the main reasons hybrids get such great mileage.

The RX's brakes, however, are horrendous. Just as in the first hybrid I ever tested, the RX's brakes engage when you push down on the pedal, then release briefly and engage again. It's a disconcerting feeling that likely hampered hybrid sales when they were first introduced. Oddly enough, Toyota's redesigned Prius has excellent brakes, with none of the hesitation that the RX displays. Those engineers clearly didn't work on the RX's brakes.

The acceleration is just as stilted. When you tap the gas pedal, the engine — which often shuts off at idle — kicks on with a lurch before there's any get-up-and-go. Again, this is a hybrid trait of the past. The new 2010 Prius and Ford Fusion Hybrid don't act this way. In all other performance metrics you'll experience on a daily drive, from highway passing to steering feel, the front-wheel-drive RX I tested is acceptable — if not good — for its class. There's little to no engine noise, even when the gas engine is running full tilt.

The suspension is slightly on the cushy side, but luxury buyers expect such comfort. I never expected a sportier driving experience in a Lexus crossover.

One bonus of Toyota's hybrid system in the RX is the ability to drive in electric-only mode up to 25 mph. This is a great thing to use in bumper-to-bumper commutes, as I recently discovered in the Prius. I engaged the RX's electric mode on my morning commute, and it lasted nearly 2 miles before running through the battery charge. The Prius topped out at 2.4 miles before it switched to gas power on my morning commute. However, I was only able to use the EV mode twice during my week-long test drive, with the car always citing not enough charge to switch over. The Prius' EV mode at least turned on during every drive I took, even if it didn't always manage 2.4 miles.

I averaged 26.6 mpg during my test, which involved four days of my daily 50-mile round-trip drive to work in very heavy traffic, which should boost mileage in a hybrid vehicle. That bests a four-cylinder Toyota Camry's 26 mpg combined, but the EPA rates the front-wheel-drive RX I tested at 32/28 mpg city/highway and 30 mpg combined. Since I rarely used the air conditioning and temperatures were mild, in the 50- to 60-degree range, I was a bit unimpressed with the RX's real-world results. Still, most crossovers this size barely break the 20 mpg combined figure. The standard RX 350 rates just 21 mpg combined.

An all-wheel-drive version of the RX 450h is available. It gets 30/28 mpg city/highway and 29 mpg combined.