The partnership with Alfa Romeo ended during the 1979 season, the team's first with young Brazilian driver Nelson Piquet. Murray designed the full-ground effect BT48 around a rapidly developed new Alfa Romeo V12 engine and incorporated an effective "carbon-carbon braking" system—a technology Brabham pioneered in 1976. However, unexpected movement of the car's aerodynamic centre of pressure made its handling unpredictable and the new engine was unreliable. The team dropped to eighth in the Constructors' Championship by the end of the season. Alfa Romeo started testing their own Formula One car during the season, prompting Ecclestone to revert to Cosworth DFV engines, a move Murray described as being "like having a holiday". The new, lighter, Cosworth-powered BT49 was introduced before the end of the year at the Canadian Grand Prix; where after practice Lauda announced his immediate retirement from driving, later saying that he "was no longer getting any pleasure from driving round and round in circles".