Swedish Söndagsseglare (lit. Sunday sailor)Someone who is bad at something (e.g. driving a car), usually due to inexperience.

https://sv.wiktionary.org/wiki/s%C3%B6ndagsseglare From the notion of a casual sailor who only sails on Sundays. Det är någon söndagsseglare som kör på cykelbanan igen = There's some Sunday sailor driving on the bike path again