I wonder if anyone has the same problem that i have? My speedo malfunctions and drops periodically. This can happen at any time. However after about driving for say 10 miles, it suddenly springs back into life.

Any suggestions, the other thing I notice is that the car jerks a little straight afterwards and even the sound on the radio decreases.

Kind of weird.

Alternator/regulator problem maybe?

This is often an issue with the instrument cluster itself if it affects all the displays (i.e. everything hits 0 then comes back to life). The best resolution is in fact to have the cluster repaired, which can be done for around £99 and can be returned within one day of being received.

If the speed drops off on its own, but all other displays behave correctly, its a VSS (Vehicle Speed Sensor) fault - this needs replacing and sits on top of the gearbox.

I had this happen to my old MK1 04 Reg Focus. Driving along and the speedo would just drop to Zero.

Thought it would be the VSS so got it replaced but it didn't fix it.

In my case I needed a new ignition coil pack. That fixed it straight away.

I was relieved as getting the instrument cluster replaced or repaired can be expensive.

Usually jerky engine, failing speedo and radio volume (AVC) is classic symptoms of a failing VSS.

The AVC (auto volume control) is linked to vehicle speed and is designed to increase radio volume to counteract road/engine noise at speed.

A new VSS is less than £20 (including mounting pin) on ebay and a half competent tinkerer can change it themself in about an hour tops saving labour costs.