As so many of us prepare for our annual drive north for the Christmas-New Year holiday, I question whether my driving at a carefully considered level over the speed limit is the speeding that is responsible for so many deaths.

In my column in The Herald today I look at the various forms of speeding I encounter, from the oblivious yabberer (always a woman) to the insane, criminally reckless 160kmh-plus rat (always a man). Then, of course, there's me and probably you. We calculate the 10 per cent margin and drive within it, preferably at the upper end, and setting the cruise control allows us to get closer to the margin's limit. I have another calculation to make, too, and that is the amount my late-model car overstates the actual speed, and it is close to 10 per cent too! Aah, but don't label me a reckless speedster just yet - I like to keep the second 10 per cent as a reassuring buffer and stick within the first 10 per cent. That's not speeding, is it?

There's good reason rather than generosity for the 10 per cent margin, by the way, and that is Australian Design Rules setting plus or minus 10 per cent as permissible error for the speedo of cars built before July 2006 and sold in Australia. You can hardly be booked, fairly, for driving within tolerances set by government. Cars built after July 2006 were required to have speedos that did not read less than the actual speed.

I believe that the safest driving is driving with the stream, and even the RTA accepts that speed differences, low or high, are a danger on our roads.

Is speeding acceptable if everyone is speeding? If it is within the 10 per cent margin is it speeding?