The RX300 has a 201bhp 3.0-litre V6 petrol engine mates to a five-speed automatic gearbox with Tiptronic-style controls. It's more than powerful enough for safe overtaking, but performance was improved significantly with the introduction of the RX350 in 2006. Refined and more frugal, the newer engine makes the RX a little more satisfying to drive and 0-62mph takes 7.8 seconds while economy is 25mpg.
The RX400h is quite different. It features a 3.3 litre V6 and an electric motor to power the front wheels, plus a second electric motor to power the back wheels. A clever system allows it to run whichever combination is most suitable and will shut down its petrol engine whenever it can to save fuel. This makes it utterly silent when stationary or moving at slow to medium speeds.
A CVT gearbox keeps the engine revs down too, so it's very refined, but make no mistake it's quick with a 0-62mph time of 7.6 seconds and superb in gear pace. The performance has been optimised to deliver its best at motorway speeds.
There's a choice of conventional coil springs or air suspension (in the top-of-the-range SE-L), which you can adjust, depending on the road conditions. The RX has permanent four-wheel drive and the traction control system decides whether to supply power to the front or rear wheels. It's not as tall as many 4x4s, but doesn't feel that nimble, with considerable body roll when cornering briskly while the steering lacks feel.
However, ride comfort is exceptional and the RX is superb on the motorway. The RX400h model feels little different on the road, although under hard acceleration it can feel like a front-wheel-drive car as the rear electric motor can only deliver a small amount of the total available power.