A3 (Slovenia), a motorway in western Slovenia

A3, a motorway in Austria

A-3 Skywarrior, a strategic bomber manufactured by Douglas Aircraft Company

Audi A3, a model of automobile

A3 road (England), a trunk road connecting London to Portsmouth

In town and country planning in the UK, A3 is the code for permission to use specific land or premises for restaurants and cafés.

A-3 Falcon an attack aircraft manufactured by the Curtiss Aircraft Company

Bundesautobahn 3 (Germany), an autobahn connecting Wesel to Passau

Alabama 3, as the United States alias of the London band. (Because of legal trademark implications, the band is known as "A3" in the United States.)

Aegean Airways IATA code

A3 Motorway (Italy), connecting Naples to Reggio Calabria

A3 freeway (Romania), a freeway, currently in construction, linking Transylvania to Bucharest

A3 road (Northern Ireland), a road in Northern Ireland connecting Lisburn to Middletown

USS Grampus (SS-4), a Plunger class submarine of the United States Navy

A3 (Switzerland), a motorway connecting Basel to Sargens

Interstate A-3 an "interstate" highway in Alaska.

HMS A3, a British A class submarine of the Royal Navy

Abrial A-3 Oricou, a French touring aircraft designed in 1927

The A3 Air Operations Branch of the UK Joint Force Air Component Hedquaters

A3 road (Luxembourg), a motorway in southern Luxembourg

ARITH-MATIC, as the former name for this programming language

Anytime, anywhere, anyplace, an SMS abbreviation

A3, a paper size defined by ISO 216

A3, a musical note, the A below Middle C

HLA-A3 is a Human MHC Serotype HLA-A

LNER Class A1/A3 a Pacific Locomotive Designed by Sir Nigel Gresley including the famous No 4472 Flying Scotsman

The A3 Champions Cup, also known as East Asian Champions Cup. A Club Football tournament for the league champions of China, Japan and South Korea

Alpha Trion, as the former name of this character from the Transformers Series

A3 highway (Portugal), connecting Porto to Braga

Autovía A-3, a Spanish autovía connecting Madrid to Valencia.

A3 (Croatia), a motorway in northern Croatia

Tasman Highway, a state highway in Tasmania