IN THESE days of size zero models, the quest for the body beautiful and faddish diets, it seems almost absurd to recommend something that comes in XL size.

Yet the Altea XL demonstrates that being big doesn't necessarily mean being ugly.

In fact, SEAT's over-sized people carrier retains the pleasing lines that made the original Altea something of a sporty choice in the medium-sized MPV market.

SEAT reckons the XL version is a family estate car but it really has a foot in two camps - that of practical estate car and roomy MPV.

It's only when you park an Altea next to an Altea XL that you really notice the difference. The XL is almost 19 cm longer than the standard car and most of the length is aft of the back doors.

This stretch means the sliding rear seats can move another 2cm and the boot is usefully larger. If you don't have any kids, it is entirely possible to slot a mountain bike into the luggage compartment without removing a front wheel. If you do have a family then the 635-litre load capacity can swallow a push-chair and all the usual paraphernalia with ease. It's a shame the rear seats still don't fold flat, however.

And that's about it, really.

There isn't a great deal more to the Altea XL over the standard model beyond the massive boot.

The XL costs a bit more (prices start from £12,995 for a 1.6 petrol Reference) and the equipment mix is slightly different (roof bars are standard and you can get one with a "factory fitted" Tom Tom satellite navigation unit) but in most other respects it is virtually the same car.

The XL's face shares the bold radiator grille, sloping bonnet and distinctive cat's eye headlamps, while the signature SEAT dynamic line is clearly visible from the side. It starts at the rear wheel and arcs over and up into the front arch - nicely breaking up the side profile bodywork and creating a sense of motion. SEAT liked the design so much it used it on the Altea, Altea XL, the Leon and the Toledo. Soon you'll see it on an Altea off-roader, as well.

The visual differences are more obvious around the back where the tail lights now split between the boot and the body. Oh, and the door mirrors are a bit bigger as well.

Familiarity - and a few extra inches - hasn't bred contempt for the smart looks. The Altea XL is very sporty for a people carrier.

Sadly the stretched chassis hasn't allowed for the addition of a third row of seats. Apparently the Golf platform used for the Altea cannot be re-engineered for seven seats so the Altea XL remains stubbornly five passengers only.

That's something of a drawback in the MPV class where cars like the Vauxhall Zafira and the Citroen C4 Grand Picasso can all carry a full load of seven people. In fact, seven seats has become the norm in this sector. Nowadays, only the Altea and the Ford C-Max don't offer them.

I'm not so sure this is a major problem, however, because all the evidence shows that owners of seven seaters rarely use the full complement of chairs at their disposal. And if you only need five then you're paying for an extra row you just don't need.

The sliding rear seat is a boon, however. Need a bit of extra room in the boot? Then shift one of the seats forward. Still not enough? Then move two or all three for the maximum luggage capacity of 635 litres. If the journey's going to be a long one your passengers can stretch out in comfort by sliding the seats backwards.

The cabin is packed with cubbies and storage compartments, too. The rear centre console has a storage case, there are small boxes beneath the seats, cup-holders front and back and deep magazine pockets on the front seats.

The picnic tables fitted to the front seat backs are a let down, though. Made of flimsy plastic, they point at such a downward angle you couldn't eat off them for fear of your lunch ending in your lap. A heavy can would made the slope even worse. I suspect they won't be used all that much.

The Altea XL is available with six engines - split equally between petrol and diesel - but only two specifications: Reference and Stylance. Every model has a generous helping for equipment including air conditioning, four electric windows, cruise control, an MP3 compatible CD player with AUX in socket, ABS, traction control, twin front airbags, side and curtain airbags and central locking.

The Altea on test was fitted with the 2.0-litre TDI unit that delivers 140PS at 4,000 rpm and 320 Nm of torque between 1,750 rpm and 2,500 rpm.

Performance was strong with decent acceleration and easy cruising. SEAT claims a top speed of 125 mph and 0-62 mph in 9.9 seconds, but surprisingly I was unable to get anywhere near the claimed 47.9 mpg combined fuel consumption. In a week of fairly easy driving that consisted mainly of longer trips on well surfaced A roads the Altea's fuel computer reported an overall diesel consumption rate of 42.3 mpg. I expected better.

The 2.0-litre feels perkier than its older 1.9 Tdi sibling and it is quieter throughout the engine's operating range. There was no detectable vibration through the steering or the gear knob. At cruising speeds the car was acceptably quiet apart from a slight wind rustle generated by the roof rails.

Being based on a Golf, the Altea receives the same basic suspension set-up. The front is suspended via an aluminium subframe and the rear is a sophisticated multi-link set-up that has caused the VW group plenty of sleepless nights since it was designed for being too costly compared to cheaper rivals.

The expensive components translate into an unusually composed ride and excellent handling for what is full fat MPV. SEAT reckons the XL has a slightly softer ride but driven back-to-back with my family's own Altea I couldn't detect much of a difference. The XL still felt quite stiffly sprung for a family hold-all.

The brakes are secure and predictable. Switchable traction control software is standard across the range. It works in conjunction with the engine management system to prevent wheel spin or skids.

Buyers can also choose the very latest electronic stability control system and emergency braking assistance which increases brake pressure in an emergency.

The six-speed gearbox offered a precise change and easy cruising.

Instrumentation is the same as the standard Altea. The speed readout is clear and easy to read and the climate control set-up easy to adjust. An MP3 CD can play ten hours of music per CD. Once again it's easy to adjust but the sound always seemed muddy and indistinct to my tone deaf ears. The Altea's cabin plastics aren't soft but they look to be very durable and are easy to clean (vital if you have small children).

At a time when some manufacturers change their models faster than their underpants, it's hard to get too excited by what amounts to just a larger boot. SEAT probably wouldn't have needed the Altea XL if the Toledo hadn't tanked sales-wise.

Given the public's antipathy towards the Toledo's bulbous boot, the stretched Altea makes sense as a better-looking alternative.

For many families the standard Altea will be enough, but if you have teenage kids or regularly carry lots of cargo then the XL-size could be the solution to your problems. And the Altea XL does hold one major trump card over its rivals - that of highly competitive pricing.

SPECIFICATION

Engine: 2.0 litre direct injection turbodiesel
Max power: 143 PS
Torque: 320 Nm
Max speed: 125mph
0-62mph: 9.9 seconds
Av fuel consumption on test: 42.3mpg
Standard equipment: power steering, six airbags, traction control, electric windows, roof rail, space saver spare tyre, MP3 compatible CD player with a minimum of six speakers, climate control.
What the papers said: "A marketing department's nightmare but a good family car, because what families need is room." 4Car.