Room for the kids, the dog and the kitchen sink

Just as the statisticians tell us that families are getting smaller, so the car makers begin to offer vehicles with more seats. To prove what an odd thing the car market is, these new seven-seaters (and even eight- seaters) are proving increasing popular.

More extraordinary is that it took manufacturers so long to offer cars with more than five seats. The turning point was the invention of the MPV (multi-purpose vehicle), or "people carrier". Chrysler gave it to the Americans in 1983 just before Renault gave it to Europe (with the Espace) a year later. These minivan-like vehicles eschew the conventional and wasteful "three-box" format of normal saloons (one section for passengers, one for the engine, and one for the luggage) and offer "one box" styling that devotes all of the body to passengers. The new Ford Galaxy MPV is a seven-seater, while the same-size Mondeo can accommodate only five.

Not to be outdone, makers of estates and big 4x4s are increasingly offering seven-seater options, by stealing some of the boot space for passengers. So if you have a big family and need more than five seats, you've never had so much choice.

Space/versatility:

The key to any seven-seater, and an area where the new MPVs dominate. All new MPVs, as well as the old favourite, the Espace, have rear and central seats that are comfortable for adults. The seats can also be taken out, so the vehicle can perform the alternate roles of people carrier and removal van. Their extra height over estate cars is a carrying boon.

The Peugeot 806/Fiat Ulysse/Citroen Synergie (same car, different badges) can be had in roomy eight-seater guise, although the Ford Galaxy/VW Sharan (again, same car different badges) comes with either six or seven seats, but has a longer cabin. Least roomy for the sixth and seventh passengers are the estates: their rear-facing bench seats are for children (under about 12) only.

The Land Rover Discovery's sixth and seventh seats are side facing. As with the rear-facing seats in an estate, they're often popular with children who seem to appreciate the better visibility such a set-up offers. The bigger Mitsubishi Shogun and Toyota Landcruiser, whose extra seats are forward facing, are significantly roomier than the Discovery.

Early MPVs had poor boot space when all seats were filled. Newer ones, such as the 806, are much better, although you'll have to stack the luggage on top of itself. When estates and 4x4s have passengers in the boot area, there is hardly any space for bags.

Driver appeal:

MPVs have made big strides recently. The Galaxy and Sharan drive almost as well as a good saloon, and are well ahead of the Peugeot/Citroen/Fiat and the ageing Espace, let alone the Nissan Serena.

Like 4x4s, MPVs have high driving positions, which give a commanding view of the road. The flipside is the high centre of gravity and, occasionally, the alarming body roll. The seven-seater Land Rover Discovery (Britain's best selling 4x4) is particularly roly-poly; the seven-seater Mitsubishi Shogun is better on road, if less accomplished off it.

No MPV or 4x4 can beat a good estate on the tarmac. The best seven-seater estate is the marvellous Mercedes E-class, which has just gone out of production, although it is still on sale in the UK. The new E-class estate is due here in the autumn. Just as good on the road, if not quite as substantial or as beautifully wrought, is the much-cheaper Renault Laguna seven-seater estate. Also impressive is the excellent Volvo 850 estate. The big, old- fashioned Volvo estates are nowhere near as good to drive, but they do feel safer and more stable than most MPVs or 4x4s.

Performance/fuel economy:

Estates such as the Laguna start with an advantage: they're usually lighter than 4x4s or MPVs, aiding both acceleration and mpg. That said, the briskest seven-seater of all is the V6-engined Galaxy and Sharan, which feels almost like a sports car in a straight line. The thirstiest is the V8-engined Land Rover Discovery, which is wickedly profligate with the unleaded.

Most four-cylinder petrol versions of estates offer decent verve; the same is true of most MPVs. 4x4s are more slothful, thanks to all that heavy off-roading hardware under the floor, which is redundant unless the road turns to thick mud or snow.

Safety:

Less clear cut than the other categories; it varies enormously between individual models. As a general rule, estates are the safest, especially the Mercedes and Volvos. They are more stable in tricky corners and most safety tests also suggest that they protect better in accidents.

MPVs and 4x4s, despite their bulk, tend not to do so well. MPVs usually site their front passenger and driver nearer the nose of the car (so in a head-on accident, there is less space for absorbing the shock); the lack of a boot also affects the rear crumple zone space.

4x4s have bulk on their side, but recent safety tests in Australia suggest that vehicles such as the Discovery are less protective in a crash than large saloons or estates. Many 4x4s still fail to offer driver or passenger airbags as standard.

Nonetheless the bench seats typically offered in the rear of estates, for children, are vulnerable to severe tail end accidents; they also provide poor lateral support in the event of a side intrusion. The forward-facing conventional seats in an MPV tend to secure occupants better.

Costs:

Seven-seaters - be they estate, MPV or 4x4 - hold their values better than conventional saloons or hatches. The lowest depreciator here is the Mercedes estate, especially in its cheaper four-cylinder guises. The Renault Espace and Land Rover Discovery also have good reputations for depreciation - potentially the biggest cost in car ownership. Newer cars like the Galaxy and Sharan also hold their values well.

The Laguna is the cheapest car here to insure. 4x4s tend to be more expensive to cover than MPVs or estates.

Conclusions:

Unless you regularly journey up snowy passes or cross country, forget about 4x4s. They're too expensive to buy and run, too cumbersome and too noisy. On the road, MPVs and estates are much better to drive and more comfortable. If you need four-wheel drive and wish to carry more than five people, the best options are the giants of the field: the Mitsubishi Shogun or the Toyota Landcruiser.

If you regularly carry more than five adults, need to haul seven people and lots of luggage, or frequently have to lug bulky or high loads, the MPV is the clever choice. An estate car just can't match its versatility. The best bet is either the Ford Galaxy or the Volkswagen Sharan: they serve up both carrying capacity and driving enjoyment. If you can afford it, go for the sublime V6 version.

If the sixth and seventh seats will only ever be used by children, then stick to an estate car. They are, unsurprisingly, the most car-like to drive, and therefore the most reassuring and familiar. The best value model is the excellent new Renault Laguna. But, if you can afford it, choose the Mercedes. A second-hand E-class estate, although still pricey, invariably makes a fine long-term buy.