So it was with our latest long term Vectra - the diesel-engined 2.2 CD. But one of the few drawbacks to running a string of test cars is that just when you've got used to them - they're whisked back to the manufacturer.
In the last couple of months, the Vectra has loosened up noticeably - offering more lively performance and increasing fuel economy as the engine settles down to its own rhythm. It's now a much smoother operator than when I took delivery six months ago, and it hasn't put a foot wrong in the 6,000 miles covered since.
The only observation I would make, is that the Vectra's thirst for oil appears to have increased since my last roadtest report. There are none of the smoke signals to indicate excessive oil burning, but it's demanded a couple of litres of the black stuff in the last few weeks via the extremely useful central display panel in the centre of the dashboard.
This helpful bit of kit offers all the usual services you'd expect to find on the average trip computer, but also tells you when you're about to run out of petrol or windscreen wash fluid and warns you if a bulb has blown.
Unfortunately, it couldn't warn me about the projectile a large truck picked up some forty yards ahead of me and hurled at my windscreen. The crack as it impacted almost had me diving into the footwell for cover, but once I registered that the source of the noise was in fact a piece of grit and not an armour-piercing bullet from a high velocity rifle, I pulled myself together and called the chaps at Autoglass.
Being an internet evangelist, I suppose I should have booked online at www.autoglass.co.uk but even us cyber-workers are still seduced by the simplicity of an 0800 freephone number, written in large friendly numerals on the front of an account card.
After giving all the particulars over the phone to a polite call centre operator, in a little over 24 hours, they sent an equally courteous technician round to replace the windscreen at our offices in Peterborough. The whole experience was about as pain-free as one could wish for - if only it were as easy to get an appointment with a doctor.
Six months with the Vectra has been pretty pain-free too. I'd be exaggerating if I said it was a particularly exciting experience, but one of the major attractions of the company car is hassle-free mobility for the driver - and the Vectra fulfils this role with quiet aplomb.
In its run-out year, Vauxhall's ageing fleet campaigner has come a long way since it was launched to a less than rapturous reception in 1995. The folk at Luton - and perhaps more importantly - Russelsheim - have learned a lot from the experience and applied it to developing the new Vectra, which promises to be an altogether different beast.