We drove the RX400h in motorway conditions, up steep mountain roads and over twisting, jinking B-roads. Like its non-hybrid sibling, the RX400h is still agile and composed, as well as refined and quiet. But we also discovered that the RX400h does demand a very attentive driver if it's to deliver the economy and low emissions promised. For example, drive a Prius with a heavy-ish right foot and no thought about fuel economy and it will still give you a better than average return. I tried this approach with the Lexus and ended up getting, according to the trip computer, little more than 20mpg. When I asked a Lexus engineer about this, he said that you have to make a conscious decision whether you are going to drive for economy or performance. In a car that weighs nearly 100kg more than its non-hybrid sibling, you cannot have both.
Which means, simply, that if you drive the RX400h hard, it'll be no more fuel efficient than a caned RX300, and possibly even less so considering the extra weight. As with the Prius, the RX400h will give its best in urban traffic, where the engine will shut down and leave the jam-creep to the electric motors.
The RX400h will, inevitably, be compared to diesel-powered rivals and rightly so. A BMW X5 3.0d, for example, will return 40.4mpg combined. Lexus would argue that the BMW is a much less powerful alternative, but the Sport version will reach 130mph and 0-62mph in 8.6secs, which is hardly paralytic. Again, the Lexus hits back with much better fuel consumption around town, as well as a CO2 output far lower than the BMW's. That, of course, will be of huge benefit to company car drivers.
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| We struggled to get 20mpg when pushing on |
And that's a crucial point. If you are going to consider an RX400h, you'll need to think long and hard about how you use your car. The more urban trawling you do the better, whereas those who do mainly motorway miles should think again.
So if a green campaigner remonstrates, point out that your Lexus produces less harmful CO2 than a small family car with half the power. And
then tell him to mind his own sodding business.
