EITHER I'm shrinking with old age or the Vauxhall Vectra is getting bigger. I haven't been behind the wheel of Vauxhall's prime repmobile for a while now, so my last long-term drive was in the original model. Climbing out of our long-term Mazda6 2.3 Sport (itself quite spacious) and into this car, it felt as though I was boarding the Queen Mary.

Both these vehicles are supposed to be upper-medium contenders, so it just goes to show what a difference there is as this sector becomes more and more fragmented. Manufacturers either seem to be going for big and comfy – as with Vectra and Citroen C5 – or athletic and sporty – as with Mazda6 and Ford Mondeo.

So how does the Vectra face up to the Mazda6 – which has just walked off with the Fleet News Award for best upper-medium car? Well, that depends. If I had a big family to transport at weekends and loads of samples to take to customers in the week, the Vectra would be the preferred choice with all that space. But if I wanted to impress the neighbours and push it to the max round the corners, it would have to be the Mazda.

After a week behind the wheel of the Vectra, with its 2.2-litre turbodiesel engine, I have found a few things I like about this car but a lot more that drive me mad.

The good points first. The seats are solid and supportive with good lumbar adjustment. Despite its size, the car is returning well over 40mpg, a figure that would have been unheard of 10 years ago. For the price, specification is good – driver, passenger and side airbags, ABS brakes, traction control, CD player, central remote locking and air conditioning all come as part of the package, although alloy wheels cost an extra £400.

Now to the bad points. Despite its size, there is not enough space behind the wheel for my 6ft 3in frame, so I can't put my knees together under the steering wheel. And why has Vauxhall tucked the hand-brake away under the middle armrest, so I have to twist my arm every time I want to use it?

Moving to the indicator stalk, things take a turn for the worse. The idea is that you just nudge it when you want to change lanes on the motorway, and nudge it further for turning at roundabouts or junctions.

The trouble is, it doesn't work. If you want the indicator to stay on, the car seems to turn it off and if you want it to turn off, it stays on. It almost feels as though the car is playing me up on purpose sometimes.

But what baffles me most is how Vauxhall can make a pig's ear of a simple device like a fuel filler cap! It only opens to 90 degrees and then the catch that holds it shut scrapes across the back of your hand when filling the car up.

It's a shame that a car that does so many things right can do so many other things wrong as well.

Company car tax bill 2003/04 (22% taxpayer) £65 per month