Even the most insane tuners have realized if they want to stay in business, they have to make greener cars. AC Schnitzer for instance has come up with a BMW Z4 that needs 3.8 liters of fuel per 100 km, and emits just 99 g/km Co2.

AC Schnitzer 99d BMW Z4 is powered by a 2.0 liter four-cylinder diesel engine In its standard form it has 163 HP and 380 Nm, but with AC’s treatment it delivers 190 HP and 420 Nm of torque.

That astonishing fuel economy is a result of an extensive weight reduction program AC Schnitzer has applied to shed off 230 Kg (507 lbs). So while it can do 0 to 60 mph in 6.9 seconds and reach a top speed of near as makes no difference 150 mph, it also manages 3.8 liter per 100km with 99.18 grams of CO2.

It’s great, but at 149,000 Euro it does not make any sense at all! I mean the whole point of this car is reduce your costs, but you have to pay Ferrari money for it.

AC Schnitzer will showcase that car at the 2011 Geneva Motor Show along with the ACS5 Sport S. The latter based on the BMW 5 Series is not built for economy, it’s built for fun. It has a modified 4.4-litre twin-turbo V8 developing 540 HP and 750 Nm, good for a 0 to 100 km/h acceleration of 4.5 seconds and top speed of 320 km/h! That is more like it.