Even as sustainability became a bigger topic, AC Schnitzer stayed true to its sporting genes, and the 99d showed why that was possible with a clear conscience. The engineers took the engine of the 320d EfficientDynamics Edition, raised its output from 163 to 190 hp and at the same time cut CO2 emissions from 109 to 99 g/km. The 99d was a technology carrier and was never for sale.
AC Schnitzer converted the Z4 to diesel with a matching drivetrain, using the most efficient diesel BMW offered at the time. With 420 Nm the 99d reached 100 km/h in 6.9 seconds and a top speed of 235 km/h, while using only 3.8 litres of diesel per 100 km. At 99 g/km it emitted less CO2 than any BMW production car then available. AC Schnitzer called this sum of measures Efficient Performance.
Weight saving played a big part. A lightweight lithium-ion battery replaced the usual lead-acid unit, and a lightweight silencer system ended in a central chrome tailpipe. The unsprung mass fell by 35 kg, thanks to lightweight brakes and one-piece forged Type VIII wheels weighing only 7.9 kg each, fixed with titanium bolts. According to experts, that made the 99d feel as agile as a car 335 kg lighter overall.
Continental developed the BLUECO tyre in 225/35 R 19 together with AC Schnitzer to reduce rolling resistance. The body sat 30 mm lower and carried light carbon aerodynamic parts, from the front spoiler and wings to the rear apron insert, roof and boot lid, while the RS coilover suspension was tested on the Nordschleife. An integrated iPhone 4 gave access to on-board computer data such as actual fuel consumption and particulate filter status.
Key facts
- Base: BMW Z4 with the 320d EfficientDynamics engine
- 190 hp (140 kW), 420 Nm
- CO2 emissions: 99 g/km, consumption 3.8 l/100 km
- 0 to 100 km/h in 6.9 s, top speed 235 km/h
- Unsprung mass reduced by 35 kg
- Sachsenring lap: 1:42.40 min, fastest diesel and fastest Z4 there
