Audi does not build many cars like the Audi A8 D3 with gasoline engine, made in small numbers. Its designer of record is Miklós Kovács.
What is underneath
Under the skin sits gasoline engine. These are manufacturer figures carried by Wikipedia and Wikidata, not road-test measurements.
Its place in the line
Nearby in the Audi catalogue sit the Audi 200 and the Audi 225.
The money
EPA combined economy is 22 mpg, about $3,900 a year in fuel at the EPA's assumptions. Condition, mileage and specification move any single car a long way from a headline figure.