Why does your speedo go so much faster than your car?

Published: 27 February 2012

Ever wondered why the speedometers in modern cars have such high readings stretching way beyond the car’s actual top speed?

I do on a nearly daily basis – and in fact have blogged on this before. It’s incredibly frustrating when only a quarter of the dial is taken up by relevant speeds of up to 70mph. You know, the useful bit you’ll actually be using every day.

Unless you drive a Bugatti Veyron on the autobahn as part of your daily commute, I’m just not that interested in 100mph+. The realms of 200mph are surely just cloud cuckoo land for most of us. Yet most manufacturers persist with squeezing the most relevant parts of the speedometer into a pie chart section your maths teacher would have called statistically irrelevant.

Crazy speedometer calibrations: the worst offenders

So in the latest issue of CAR Magazine, we did a spot of research. You’ll find it in the new March 2012 issue of CAR out now on page 27.

One day we went down to the car park and poked around all the test cars and long-termers in our car park, comparing the v-max on the speedos with the claimed maximum speed recorded for each. The results make interesting reading:

Speeding offences: the cars with the most imaginative speedos

Mini Countryman 30% of dial unused
Audi A1 26% of dial unused
Skoda Superb 26% of dial unused
Seat Alhambra 25% of dial unused
VW Touareg 25% of dial unused
BMW M5 23% of dial unused
Audi RS3 23% of dial unused
Jaguar XF 22% of dial unused
Kia Optima 22% of dial unused
Audi A1 21% of dial unused
Ford C-Max 17% of dial unused
BMW 1-series M Coupe 14% of dial unused
Infiniti M35h hybrid 14% of dial unused
Saab 9-5 11% of dial unused
Mercedes CLS 6% of dial unused
Honda CR-Z 0% of dial unused (NB digital read-out)

Should more manufacturers switch to digital, like the very honest Honda CR-Z and Nissan Leaf (tellingly two hybrids, with less claim on speeding matters)? What about the space-efficient non-linear calibration used on some Skodas, which compact speeds above 100mph into smaller increments? And are the VW Group the worst offenders, as our snapshot suggests?

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By Tim Pollard

Group digital editorial director, motoring news magnet