Four seats or two?

And so it begins again.

Now that we have Heather's new car - a sensible family estate - my thoughts start to turn towards replacing my own car.

When I bought my current car (a BMW 3-series saloon) nearly two-and-a-half years ago, it was always with a view to it being our main family car until such time as we had a second child or it reached 50,000 miles (the milestone beyond which dealers start to get sniffy about part-exchanges). Having ticked the first box with the arrival of Toby, I am on course to hit the magic 50k mark shortly after Christmas, which gives me five to six months to make a decision and place an order.

Broadly speaking, the decision facing me is whether I want a car with four seats, or one with two.

Two seats equates to something small and sporty for me. (I've got the recently-updated BMW Z4 or possibly the new TT squarely in my sights.) There are obvious disadvantages to this, in particular the fact that we would have no back-up to carry the boys if Heather's car has any problems. But in the past I have always alternated sensible cars with fun ones - Citroen Saxo, Peugeot 306 GTI-6, Lexus IS200, Audi TT and my current 3-series - and the (admittedly selfish) desire to have something fast and impractical is a strong one.

Four seats means buying something large and family-friendly, that will carry everything we need for two adults and two children to go away for a week. We can probably just about manage it in Heather's car (a Focus estate), although it might be a tight squeeze on long journeys - we're away for a week next month, which will be a good test of how practical and comfortable that is.

Going for another family car would mean either a large saloon (a 5-series or Audi A6, say), a large-ish estate (just no, okay) or - whisper it quietly - a 4x4 or SUV (probably something like a BMW X5). I've never been a fan of big cars - my 3-series is about as big as I would ever really want, and more than roomy enough on the inside - so I would take some convincing before heading for the next size up. But the arguments in favour of having two cars suitable for the family are also quite strong: Heather's car would then be the day-to-day family car, with mine being used for longer trips when the extra space and comfort are at a premium.

That's the dilemma, really. Buy a car for the family that will be a compromise solution for me 50 weeks of the year, or get one I love which is utterly impractical. Four seats versus two; head versus heart. Decisions, decisions. I can see a long summer with much hand-wringing ahead of me ...