How do they work this out, and is it payable like every few months?
Just got a bill for CHF 167 covering the period 2 Oct when I bought my car up to 31 Dec. At this rate it works out at > CHF 650 a year...?

And to all who will no doubt tell me to search the forum, I did already and the word didn't come up...

Ah, but what you didn't use was google.

http://www.zug.ch/cgi/strassenverkehrsamt/stvstin.cgi

is a verkehrssteuer (road tax) calculator for canton Zug. Don't be afraid to call them either. No doubt you'd get the most accurate information from them. Once you've done that, be good and let us all know.

As far as I remember, the calculations for road tax are specific for different Kantons. I recall that Ticino was quite different to others (see Living and Working in Switzerland by David Hampshire). I had a slight shock in Baselland recently- here it is based on the weight of your car multiplied by their factor- it's around 0.3343 (exact figure available on the BL MFK website), which is quite an increase on last year.

Slightly off topic, but my road tax came out around 650 CHF too- but I can't see how the ownership paper lists the car at 16xx kg when the manufacturers (dry) weight is 1415 kg; I've seen 1470 kg quoted in Evo magazine. Even AutoScout has it at 1570 kg. Anyone else had similar problems being overwieght?

Its payable by year. If you buy a car in the middle of the the year you will pay taxes pro rato... Check the link that gooner provided for further details...

Including driver, passenger and fuel?

That's because it's the English Forum .