Super unleaded question

No that's not real true. It's the combination of petrol compounds. More simple chain hydrocarbons have lower octane values than branched chains and aromatic rings. They're all "burny bits of petrol" but some burn better than others. High octane fuel has more aromatics etc in it.

From a reliable book source: "If the compression ratio is raised too much, the mixture, instead of burning smoothly, tends to go off with a violent and damaging bang, emitting a noise known as pinking."

Hence we're both partly right and partly wrong. Pinking and knock is indeed the same phenomenon, but the ignition method is not the issue.

Not so much surprising, I thought the vehicle would have covered enough miles to be considered run in. NOt too much an issue as the top speed is more than twice the national limit, so I doubt I would be doing that very often....

The message from "Avanti" contains these words:

I think it was the failure to reach the makers claimed top speed which was the issue, not the state of running in.

I don't know if cars are the same, but certainly bike magazines used to test bikes and I don't think I ever saw one actually reach more than 95% of the claimed max.

Yep - 5 star used to have quite significant amounts of benzene in for example, 2 star had none (apart from the odd trace)

Wot Guy said. I would be surprised if most cars actually achieved the makers' claimed top speed. Bearing in mind that they would test things like that in fairly specialised conditions.

The message from "Malc" contains these words:

Downhill with the wind behind it, if my Fiat 127 were anything to go by.

I suppose I worded it wrongly there, I know speedo's aren't accurate, when I had my MK4 Golf 1.8 T when purchased it had 39k on the odo, and it would drive up to 134mph (claimed top speed) , by the time it cover 60k the speedo would go up to 141mph, and on a couple of occasions I had similar models in front of me but newer pull over as it seems they could go no faster, .