Could this be the LS that finally catapults Lexus into the big time? The all-new fourth generation car is a big step forward over its predecessors, especially the slab-sided model it replaces. Now the design is flowing and organic rather than brutish, while the outstanding build quality and comprehensive spec levels remain.

External styling is handsome enough, this LS looks like a scaled-up version of the current GS and IS. The cabin is spacious and predictably packed with kit, but it's hard not to feel let down by slightly unadventurous design, and some very cheesy-looking wood trim. Fortunately the driving position is supremely comfortable, as are the seats for other occupants, and the LS absorbs long journeys like almost no other.

The dynamic experience has been engineered around comfort and waft, something the LS delivers supremely well. The cabin is whisper quiet at cruising speeds, with soft air suspension to smooth away road imperfections. Even with the adaptive dampers turned up to their firmest setting it never manages to feel particularly keen or sporty - but most occupants will appreciate the comfort more than they rue the lack of tyre-squealing back road dynamics.

Only one hybrid powertrain is available: the high tech combination of a silken 5.0 litre V8, a battery pack for electric running at low speed, and the world's first production eight-speed automatic gearbox. Other techno delights include a sensor that detects when the driver loses attention and sounds an alarm, plus, on the 600L, rear seats that can gently massage the occupants.

Relentlessly competent across the board - there's just one thing the LS misses - a sense of occasion to rival that delivered by the altogether grander Mercedes S Class.