As of 2015, the Buick Regal line has never had a convertible. The car features vary between model years, but they are generally two-door or four-door coupes or sedans with V6 engines and luxury amenities. Buick's convertible line is the Cascada.
The Regal was introduced in 1973 as a mid-sized luxury car at an intermediate price point. The models made from 1973 to 1977 were equipped with one of Buick's own V6 or V8 engines, as well as a three-speed automatic transmission. Luxury interior features included woodgrain trim and either bench seats with armrests or optional bucket reclining seats.
Regals made between 1977 and 1987 retained the same basic body styles, but with a redesign and with the option of a five-door station wagon in some model years. These cars had a variety of different V6 or V8 engine types.
Models made from 1988 to 1996 returned to either a Buick or GM V6 engine but added a four-speed automatic transmission. Airbags and anti-lock brakes became standard starting with the 1994 model.
The models made between 1997 and 2004 all have a stock Buick V6 engine and are only available as a four-door sedan.
Modern Regal models employ a variety of GM I4 engines. They continue to only be available as four-door sedans but have upgraded to a standard six-speed transmission.