The Lotus Grand Tourers

Any suggestions on what would cause the speedometer needle to quickly bounce up and down between 0 and around 20 kph until the speed has passed that?

Could be the speedo cable is binding at low speed, also check that it's secure at both ends. There's also a speedo drive off the gearbox, I think it's mentioned in the service schedule as something to oil or grease periodically. If cable and drive are good it may be an early sign that the speedo is going to need attention. Mine needed a rebuild a few years back after similar symptoms to what you are seeing, but it could just be a cable/drive issue so worth checking that first.

Cheers John

Like John says, primary culprit is binding speedo cable - get some oil in there, if the inner cable can be withdrawn from the sheath (can't remember if this can be done, but it may be possible) you can lube it much better. Also check the cable routing, should be as smooth as possible with no kinks or tight bends.

Thanks for the suggestions. The speedo is fairly new, and was replaced shortly before I purchased the car. I will give lubing a try.

As it's a replacement then I'd reckon something not quite right with the routing. As above check for tight bends / kinks etc. That said while it's apart no harm in a bit of lube.

Does it tick as this is often a sign of too tight a bend?

At least for the Toyota Supras, the common culprit is an elbow off the transmission speedo gear drive. Haven't looked yet to see how the Excel's speedo cable is connected and routed. The Supra w58's got a sharp, almost 90 degree elbow while the a43d's got a less problematic smooth arc elbow. Both work the same way tho, just a flexible cable that runs through them and eventually wears out at least in part because the old soap grease inside it dries out.

My car also does this every now and then. This is despite having my speedo reconditioned and fitting another speedo cable. I took care to well lubricate the cable before fitting and have tried re fitting the cable at least four times at both the speedo and gearbox end to no avail.