In what is clearly a blatant bid to appeal to a niche market defined by Spinal Tap guitarist Nigel Tufnell - whose amplifiers went up to 11 - the gearbox on the latest version of the hugely likeable Honda Jazz goes all the way up to seven.

You will appreciate that on most cars the gearbox only goes up to five - six if you're extremely lucky, but normally five. And then, as Tufnell would point out, if you need that little bit extra, where do you go? To the Honda Jazz, is the answer, which offers two more.

It offers them in a unique dual gearbox package that enables you to drive the car either manually, via push-buttons on the steering wheel, or - for those moments when you are feeling more Michael Meacher than Michael Schumacher - in automatic mode.

But not just any old automatic mode. The CVT in the car's name stands for continuously variable transmission. In order to understand this technical development as fully as possible, I steeped myself deeply in the literature supplied by Honda - and would have steeped myself still more deeply if I hadn't fallen into a strangely confused sleep directly after the sentence reading: "The steel belt is a ring of numerous steel element plates that are joined with two-layered ring bundles."

Snapping to an hour or so later, however, I realised I had absorbed the essential point, which is that, thanks to some top-grade boffinery involving synchronised pulleys, the CVT-7 does not change gear, as most automatics do, in a series of lumpy steps, but simply powers up seamlessly, from standing start all the way through to maximum speed.

In the traditional automatic, you put your foot down and then wait while the gearbox does its best to catch up with your instructions. Sometimes, in some of the cheaper or older models, whole journeys can pass before it does.

In other cases, the car will lurch into gear both audibly and tangibly, lightly tapping you on the forehead with the windscreen. This is called, in the trade, shift shock, and no one likes a shifty car, any more than they like a shifty car dealer.

Unusually in a car in this range, the CVT-7 is, in the nicest possible sense, shiftless. You depress the accelerator and the car sets off; you depress it further and it speeds up; you lift off and it slows down, and all without any lumpy or bumpy gear business. Of course, in a sense, milkfloats achieve much the same effect. But you can't get a milkfloat up to 70mph - or at least, not without a big hill and a prevailing wind. And you can't make a milkfloat sound as smooth and uncomplaining under acceleration as the CVT-7.

The other key advantage of continuously variable transmission is that it diminishes the lag-time, commonly experienced by automatic drivers, between pushing down the accelerator and experiencing any noticeable quickening in the car. There are some automatic transmissions out there that virtually oblige you to apply in writing every time you wish to speed up and overtake. I'm still waiting for the paperwork to come back from Fiat granting me permission to go round a tractor I came up behind in a Stilo last June, and I'm warned not to expect much news before April. All credit to the CVT-7 then, which lets you have the power pretty much as and when you want it.

In this context - and with all due respect to Tufnell - the seven-speed manual override seemed to me to be something of a redundancy. Obviously anyone with fond feelings for Captain Scarlet and his pals will enjoy flicking the paddle marked "7 speed mode", which puts the gear-changing under your control - or at least partly under your control. If you don't do anything, or alternatively, if you try to do too much (like trying to pull away in seventh, say), the car's automatic system kicks back in to give you a firm nannying.

Clearly, also, the aluminium push-buttons, positioned on the steering wheel where your thumbs can easily get at them, will speak loudly to a generation reared on PlayStation and play to the over-developed manual dexterity of many a student and/or person who works from home.

But always in the back of your mind, as you crouch and hop between the gears, is the memory of the caramel-like smoothness with which the car operated in CVT mode. Honda's literature cheerfully invites us to experience "the fun of fingertip shifting"; my own experiments with the flipper served merely to remind me, rather miserably, that I couldn't drive the car anywhere near as well as the car could drive itself.

In all other respects, this is the same Jazz that we spoke highly of on its launch a year ago, bringing something a little more spritzy, clean and solid feeling to a sector of the market that is swamped with blob-alikes. I drove the 1.4i DSI SE CVT-7, which sounds like an over-decorated major general.

But only the name has grown more cumbersome.