Switzerland: do Swiss rental cars have a vignette?
The honest answer is "often, but check". Switzerland sells only an annual vignette, valid from 1 December of the previous year to 31 January of the following year. So a Swiss-registered car in regular use on Swiss motorways will usually carry one. The duty to have one, however, attaches to using the motorway, not to the rental contract.
Checking is harder here than anywhere else. A sticker sits on the inside of the windscreen, so look for it and make sure it is the current year's. An e-vignette is invisible. The federal customs office's public check shows it only if the buyer set it to "publicly viewable", at purchase or later. A rental company may not have done that. If you see no sticker, ask the desk to confirm in writing whether the car has an e-vignette, or to switch its public visibility on. Do not simply buy a second one to be safe: the customs office refunds e-vignettes only in narrow cases, such as a proven duplicate purchase in its own webshop.
A car rented in France, Germany or Italy is a different story: buy the Swiss vignette yourself before reaching the motorway. It also covers Liechtenstein. Unlike Austria, Switzerland has no waiting period for online purchases. Swiss law gives online buyers no right of withdrawal, so the customs office says an e-vignette from its webshop is valid straight after purchase. If you type a foreign plate wrongly there, the webshop lets you correct it once within 24 hours of purchase. Vignetim sells the Swiss e-vignette against your hire car's plate.