The story
Blend of T + plate; T stands for tourist; emerged in Scotland in the mid-2020s for the Scottish Highlands before being adapted in other countries.
Etymology from Wiktionary, CC BY-SA 4.0.
T-plate
Today it means: A square, white sign featuring a green letter "T" attached to a rental or visitor's car; used to alert locals and other drivers that the person behind the wheel is unfamiliar with the area's roads, signaling them to give the driver extra space and patience. Full definition →