I bought this vehicle with 64K miles on it. Now I have 102K. My worse tank was 24mpg and the best was 29.25mpg. I seem to average between 25 and 27.50 with mixed driving. High speed highway (75-84) is only around 22. When I get the higher mileage it's usually when most of the driving is at lower speeds as you would expect. I noticed a review of this vehicle by someone stating poor mileage. There was either something wrong with the vehicle or it was due to poor driving habits. Way too many people blast up to the light and hit the brakes. Then they hit the gas hard taking off. Dumb-de-dumb. If you use softer driving habits you will get 26-28. You have to be thinking hybrid. Smart drivers will see the good mileage. Navigation works well with two exceptions. First is it's incredibly dumb that a passenger can not program the vehicle while the car is in motion. Second is the warning notice which displays for 5 or 6 seconds everytime you hit the NAV button. There should be a way to stop it from doing that.
Loved this car from the minute we bought it new. Nearing 80,000 miles and no complaints! Only some paint chips on door edges. Not buying a new one though. Don't like the new design and new screens. No more touch screens - uses a mouse! OMG! They went backwards!
Broke this car in on a trip through the mountains. At 200 miles, it averaged 25.1 MPG, 72 MPH. Town driving at average 27 to 29 MPG. Latest trip (Interstate and mountains) averaged 26.1 MPG., again at 72 MPH. Acceleration is both excellent and fun. This is our third Lexus (2nd RX) and it's by far the best. If your gas mileage isn't AT LEAST as good as the EPA estimate, work on modifying your driving style. Build quality for this Japanese-built example is flawless, and dealer (Classic Lexus) is extremely 'hybrid knowledgeable'.
I bought this used about a month ago with only about 60 K km. (less than 40K miles) on it. After much research I decided to use only REGULAR gas in it since it seems that Premium is more about performance than fuel economy. I'll probably throw in an additive every three months or so. Having driven it about 2500 km. (about 1500 miles), I'm averaging 8.6L / 100km. which is just over 27mpg. And that's on REGULAR Gas. My 2010 2.4L 4 cyl. Hyundai Santa Fe could not even begin to to approach these numbers. Couldn't be happier because I got a great deal on a car that was just inspected by Lexus and had all the brakes done by Lexus, and is practically new. My best vehicle ever!
My RX 400h has been the very best, most reliable vehicle I have owned; buying my first car in 1967. Gas mileage has been super, averaging 28.5 MPG since day one. it is solid, very comfortable, has lots of power and a joy to drive. I recommend this car to anyone who wants a quality, energy efficient hybrid!