The letter 'E' is the international vehicle registration code for which country?

The country in which a motor vehicle's vehicle registration plate was issued may be indicated by an international licence plate country code, formerly known as an International Registration Letter or International Circulation Mark. The sign must be displayed on the rear of the vehicle. The sign may either be placed separately from the registration plate, or be incorporated into the vehicle registration plate.

The allocation of codes is maintained by the United Nations Economic Commission for Europe as the Distinguishing Signs Used on Vehicles in International Traffic (sometimes abbreviated to DSIT), authorised by the UN's Geneva Convention on Road Traffic of 1949 and the Vienna Convention on Road Traffic of 1968. Many vehicle codes created since the adoption of ISO 3166 coincide with ISO two- or three-letter codes.

'E' is used for the country of Spain as the Spanish word for Spain is España.