Michele Alboreto (Ferrari 126C4), using qualifying tyres, eventually emerged the quickest runner at Rio with a time of 1 min 29.18 sec. Alain Prost (McLaren MP4/2) was next fastest with 1 min 29.89 sec while Rosberg's 1 min 30.60 sec in last year's Williams FW09B was considered heroic. Nigel Mansell, in the other Williams, was sixth fastest with 1 min 32.40 sec but Mansell spent most of his time conducting engine tests and had his car jump out of gear on his best lap.
Fourth fastest was Patrick Tambay (Renault RE50) with 1 min 31.30 sec while team-mate, Derek Warwick, was probably the quicker driver for his time of 1 min 34.60 sec (11th fastest) was set on race tyres which were roughly four seconds a lap slower. Elio de Angelis (1 min 31.60 sec) was fifth fastest in the new Lotus 97-1 while early pace-maker, Ayrton Senna (1 min 33.34 sec on control rubber, ninth quickest) did not drive again after crashing into Mansell's car.
Cooling problems and a broken chassis spoiled the Brabham test but Nelson Piquet managed 1 min 32.50 sec just fractionally faster than Stefan Johansson's 1 min 32.60 sec in the new Toleman TG185, both cars running on qualifying Pirellis. Martin Brundle was easily the quicker of the two Tyrrell drivers, recording 1 min 35.57 sec (11th quickest) to Stefan Bellofs 1 min 37.79 sec (14th), in both cases the Tyrrell 012-Cosworths were on qualifying Goodyears.
The new RAM 03 overheated rapidly and is in urgent need of modification. Manfred Winkelhock recorded 1 min 36.14 sec (12th) and Philippe Alliot, 1 min 38.24 sec (15th). Niki Lauda had a whole series of mechanical problems which meant only five clear laps and all those on race rubber. His time of 1 min 36.49 sec (13th) should therefore not be regarded too seriously.