Numbers first, because with the Tatra 15 they are the story: Tatra 12 (1927) Tatra 30 (1932) Tatra 52, 22-30hp. Tatra built from 1927 to 1952, the vintage years, when coachbuilders still shaped most of what was sold.
Where it came from
The Tatra 15 was a railroad speeder which was produced from 1926 to 1952 and was in service till 1972 by Tatra Kopřivnice. The vehicle had a normal sedan class car body with four doors and sitting capacity of three crew members and one driver, these were used as railway maintenance vehicle. There were three models produced over time 12, 30 and 52 each one had bigger engine than before the last generation 52 model had a Petrol, air-cooled inline four-cylinder engine which produced 30hp.
It has a two speed manual transmission and drum brakes at front and rear, while the vehicle was front engine and rear driven. The vehicle was intended to drive in both directions, for which a lifting system was installed in the middle of the vehicle to turn in the preferred direction The vehicle has the same levels of comfort as normal road driven cars, with solid axles and leaf spring suspensions at both front and rear. All three models are available for display at Tatra technical museum Kopřivnice, Czech Republic. The vehicle was seen in a 1966 comedy film Closely Watched Trains produced by Barrandov Studios.
Under the skin
Under the skin sits Tatra 12 (1927) Tatra 30 (1932) Tatra 52; it is rated at 22-30hp. Kerb weight is 1250-1430kg. Power-to-weight lands near 18 horsepower per tonne, which is leisurely, which for a car of its age and purpose is the point. The gearbox is a Two speed manual. The wheelbase is 2420-2720mm. These are manufacturer figures carried by Wikipedia and Wikidata, not road-test measurements.
In context
On a showroom list of its day it stood against the British Motor Corporation Austin 16, the Vauxhall 20-60. Nearby in the Tatra catalogue sit the Tatra 10 and the Tatra 600 kabriolet.
The money
MotorJury scores cars on the United States complaint and recall record, and the Tatra 15 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.