Plans to build the remaining stretch have existed for long time.

A "superstrada" (an almost motorway-like road, with 2 separate carriageways and interchanges) with a speed limit of 110 km/h (68 mph) exists between San Pietro in Palazzi and Grosseto, but the present road between Grosseto and Tarquinia has 90 km/h (56 mph) speed limit, with long parts of single carriageway and even some parts of 2-lane road.

The 2 proposed solutions are an entirely new motorway (with higher impact on the environment), and the upgrade to motorway standard of the present road (more environmentally friendly).

On 17 May 2017 the European Commission announced that it would be taking legal action against the government of Italy for awarding an extension of its A12 motorway concession contract to Società Autostrada Tirrenica p.A without undertaking a competitive procurement exercise in accordance with EU procurement regulations.

[1] Port of La SpeziaSanto Stefano di Magra Cinque Terre National Park Porto Venere - Lerici Media related to Autostrada A12 (Italy) at Wikimedia Commons