Looking at the bald figures, it is quite impressive what Lexus manages to eke out of the RX450h. Just 145g/km of CO2 for a chunky great SUV is impressive when most diesel rivals (and Porsche's own hybrid Cayenne) can't get within 45g/km of that. So you'll save about £115 a year in tax.
Trouble is, in the business of actually driving it about, you don't get 45mpg, you get 30mpg - the same as all the diesel SUVs. And it's not like Lexus has pushed the technology boundaries. There's no plug-in system, and the battery range is pitiful. Driven gently, it is a very smooth system, but if you enjoy driving, do yourself a favour and bypass the RX. None of the driver controls feel attached to, well, anything further down. You're basically feeding requests to a bunch of computers that make the final decisions.
The F Sport trim level brings buyers absolutely no technical or mechanical upgrades, but the smoked alloy wheels and hexagonal grille do enhance the visuals... although whether they make the RX450h worth £51,995 is questionable. That puts the £115 annual tax saving into perspective, doesn't it?
3456cc, V6, 4WD, 295bhp, 247lb ft, 44.8mpg, 145g/km CO2, 0-62mph in 7.8secs, 124mph, 2205kg
If you're an undemanding driver, meet the least intimidating SUV. It's simple to drive and rather dull.