Former champions Renault and Williams unveiled their 2009 Formula One cars before testing at the new Algarve Motor Park circuit in southern Portugal.
Spain's double world champion Fernando Alonso and Brazilian Nelson Piquet joined team boss Flavio Briatore in presenting Renault's R29 car.
Renault, eager to cut costs amid the global financial crisis, had scrapped a planned launch at Le Castellet in southern France in favour of a simple presentation at a regular test.
Williams also gave their Toyota-powered FW31 a low key debut before the German test driver Nico Hulkenberg took it out for the first installation laps.
McLaren will have world champion Lewis Hamilton at the wheel tomorrow when Toyota also tests its new car.