Start with what the A.L.F.A 15-20 HP is: a car with 2.4 L I4, built from 1914 to 1920, as the assembly line was turning motoring into an industry. What it meant takes a little longer.
What is underneath
The engine is 2.4 L I4. On the scales it comes to 920 kg. Drive goes through a 3-speed manual. The layout matters: a front engine drives the rear wheels, the classic proportion — long bonnet, cabin set back — that most people picture when they picture a sports saloon or a grand tourer. The wheelbase is 2920 mm. These are manufacturer figures carried by Wikipedia and Wikidata, not road-test measurements.
Its place in the line
In the Alfa Romeo line-up the A.L.F.A 15-20 HP has a clear place: it replaced the A.L.F.A 15 HP; it handed the line to the Alfa Romeo 20/30 HP; the factory was Portello, Milan, Italy. The cars a buyer would have weighed it against include the Dodge 30-35, the Delahaye type 32 coupé-chauffeur, the Chevrolet 490. Nearby in the Alfa Romeo catalogue sit the A.L.F.A 12 HP and the A.L.F.A 15 HP.
Owning one today
MotorJury scores cars on the United States complaint and recall record, and the A.L.F.A 15-20 HP has none: too old, too rare, or never sold there. Its value today is a collector's question, decided by provenance and condition rather than by a class average.