Considering that the roomy 2012 Lexus RX 350 can fit an entire family—in plush isolation, with confident, refined performance—its EPA mileage ratings of 18 mpg city and 24 or 25 highway aren't all that bad. Meanwhile, the RX 450h is one of the greenest family-sized vehicles, and with its well-coordinated powertrain and a pricetag that isn't all that much higher than the RX 350, it makes more sense to those who make keeping a little greener one of their priorities.
All RX 350 models now include an 'eco driving' light that simply highlights when you're driving mindfully.
That's what the EPA ratings say, but the last time we drove an RX 450h, over mixed driving conditions we didn't see anything close to the EPA rating—about 23 mpg overall, with all-wheel drive model. Although the last time we had an RX 350 we only averaged 17 mpg.
The RX 350 is no standout for fuel-efficiency, but get the 2012 Lexus RX 450h and you'll have one of the greenest large luxury wagons.