Start with what the Triumph Roadster is: a car with gasoline engine, built from 1800. What it meant takes a little longer.
The background
The Triumph Roadster is a roadster produced by Britain's Standard Motor Company from 1946 until 1949. It was sold as the Triumph 1800 Roadster (18TR) from 1946 to 1948, and as the Triumph 2000 Roadster (TRA) from 1948 to 1949.
The engineering
The engine is gasoline engine. On the scales it comes to 1800: 2540 lb. Drive goes through a 1800: 4-speed Manual transmission / manual; / 2000: 3-speed manual. The wheelbase is 100 in. These are manufacturer figures carried by Wikipedia and Wikidata, not road-test measurements.
Where it sits
In the Triumph line-up the Triumph Roadster has a clear place: it handed the line to the Triumph TR2; the factory was Coventry, United Kingdom. The cars a buyer would have weighed it against include the Holden Coupe 60. Its Triumph stablemates include the Triumph SD2 and the Triumph Renown.
Owning one today
There is no federal ownership record for the Triumph Roadster — it predates the complaint database or was never sold in the United States — so MotorJury publishes no running-cost figure for it. For a car of this age the price is set by the collector market and the condition of the individual example, not by a formula.