Group 4, with a 2-litre BMW engine. Donald Healey had returned with its SR 2-litre prototype, improved from extensive testing at Silverstone. The Unipower GT had a 1275cc Mini Cooper S engine, while the Piper GTR had a 1300cc Ford engine. Smallest car in the field was the Abarth 1000SP After their excellent result in the previous year's race, Alfa Romeo's Autodelta works team was favourites for a class-win. However, the team withdrew after the death of their lead-driver and 1968 race-winner, Lucien Bianchi, at the March test weekend trialing the new Tipo 33/3– the third driver death for the team in testing after Jean Rolland and Leo Cella in 1968. Instead it fell to the Belgian customer team VDS to run two of the older model Tipo 33/2, one with a 2.5-litre V8 engine. The GT category was still a limited field. Scuderia Filipinetti had a lock on the over 2-litre class, with both entries – a Corvette Stingray and Ferrari 275 GTB/C. The under 2-litre class was only contested by 911 privateers – the Porsche already proving to be the car of choice in this class. Alfa-Romeo and Abarth factory entries dropped out because of a customs strike, and Ferrari North America also scratched some entries. Practice The test weekend was held on 29/30 March and was marred by the fatal accident to Lucien Bianchi in the new 3-litre Alfa Romeo. Apparent mechanical failure hit the car on the Hunaudières straight, coming over the hump approaching the Mulsanne corner at over . The car crashed into a telephone pole and a transformer station and exploded. Bianchi was killed instantly by the impact. From the test weekend Rolf Stommelen, in the brand new Porsche 917, recorded a 3:30.7 over three seconds quicker than Servoz-Gavin in the Matra. Paul Hawkins in a works Lola was third-quickest with a 3:35.2. The power of the new Porsche 917 was shown by Stommelen on the first night of practice when he put in a blistering lap of 3:22.9 to take pole position. This was over 2 seconds faster than the sister car of Vic Elford. It was also 0.7 seconds faster than the lap record held by the big Mark IVs of Denny Hulme and Mario Andretti in 1967 (set without the Ford chicane present). Despite a top speed over 20 km/h slower than the Fords, this was achieved with the great advances