My TS Magna's Odometer and Speedometer are both somewhat incorrect, it seems. The speedo is off by about 8kph, and the Odo is reading 100km less than it usually does when I fill up, despite doing around the same distance. I haven't done anything to the car, it just started to happen one day.

Could it be something like a wheel out of alignment/balance? I live in a rural area with some pretty bumpy dirt roads, so it wouldn't surprise me if a wheel is out of whack.

what size tyre you running?

205/65 R15, standard, as far as I'm aware.

Tyre size will affect it more but 8km/hrs seem right to me. You might be using more fuel and thinking distance are shorter. I run richer fuel in mine seem to be work better.