Nothing major has gone wrong.
I see a lot of people referring to a loud noise/vibration when they are taking off with low revs on. I don't experience this, but I do experience shuddering in the steering when turning the wheel while crawling the car (IE 3 point turns). Are they the same problem?
I get what I think is some pinging when the car is cold. It doesn't always happen, and when it does, it only lasts a minute. When I put my foot down, I hear rattles from the engine, I'm pretty sure it's pinging. I usually run it on standard unleaded, maybe I need premium, or maybe the fuel injectors need a clean out.
The standard CD player skips far too easily. I'm not sure if this is because the previous owner treated it badly. I will look into a replacement head unit sometime.
I am enjoying just about everything of this car. I bought it second hand at 3 years old, and it only had 23,000 on the clock. I've had it about 7 months now.
I have not experienced any of the stalling problems which appear to be a common complaint in these reviews. Perhaps the previous owner had this fixed, perhaps this car didn't have the problem. The car idles quite low compared to others I've seen - around 700 revs. It's never stalled or spluttered or threatened to stall.
The performance is very good, though it's not a drag race car. The engine has quite a bit of power down low, so you can cruise around without a lot of gear changing.
The gearing of the car is quite high, so 3rd, 4th and of course 5th gear are all useful on the freeway. However, in my freeway driving, I've only needed to change down for overtaking, not for climbing hills. The car pulls very well at the 1800 or so revs it cruises along at in 5th on the freeway.
The brakes I find outstanding. I haven't had much cause to crash stop in the car, but the one incident I did have to, it stopped very quickly. I have tried crash stopping on a quiet road, and it was very hard to cause the ABS to come on. I've heard that the Vectra has big front discs, and I'll believe it.
The brakes come with a downside - the front wheels get coated in dust pretty quickly. It comes off pretty easily if you wash it often enough. Even after a month, the dust just scrubs off with water.
The clutch and gearbox are good. The gearbox has a short throw, which I like. Sometimes it can take a couple of tries to get it in first when rolling to a stop at lights, though.
The handling is very good. The car sits quite flat, and it takes a lot of effort to bring the car unstuck. The traction control kicks in late, though I heard this was deliberate. Unfortunately, I usually beat it to backing off the power, and this can sometimes have the effect of the car losing a lot of acceleration because both the car and I reduce the power.
The interior is quite comfortable, I like the seats. There's not a lot of room in the back, though, but I rarely have passengers.
There is quite a lot of space in the car, though. I took the car skiing, and on the first day, I had four people (including me), plus all our luggage, plus ski gear for about 6 people in the car. The ski hole in the middle of the back seat was handy.
There are lots of little features on the car I haven't seen in others before: headlight angle adjusters, extensive system checking on start, including brake lights and fluid levels, etc. These aren't stunning features, but they can be handy.
The fluid warnings come on when you should put more in, not when the engine is getting dangerously low. I had a coolant level light come on. Sure enough, the coolant was getting low. I find this handy because I'm forgetful and lazy, and I don't like to spend all my time on the weekends going over the car.
There are a few little things with the car. The clutch pedal squeaks a little, the steering column squeaks a little. As everyone says, the driver's foot rest is too soft. It's fine for resting your foot on, but it feels like a sponge if you try to get some support out of it when moving yourself around.
There's no place to put my wallet / other stuff in the centre console. I don't have a need for the cup holders, so I would rather just have a hole there for my wallet!
Overall, I greatly enjoy my time in the car. I was choosing between this and a Pulsar SSS. The performance was virtually the same, but the Vectra was quieter, more comfortable and a more complete car.