(from AC Schnitzer Press Release)
Tradition demands it - every (2) years, at the International Motor Show
in Frankfurt, as well as the many innovations in the AC Schnitzer
special accessories range, a very special vehicle is presented. And 2003
is no exception: The Concept Car, the AC Schnitzer V8 TOPSTER.
The basis is the BMW Z4 3.0i, in which however "no stone is left
unturned". The most striking optical feature is the enclosed bodywork,
now 13 cm wider, in colours orange / cream.
The life-giving organ which was developed in record time as a one-off
special in close collaboration with the BMW works team Schnitzer
Freilassing, is the upgraded performance version of the 4941 cc eight
cylinder, four-valve engine from the BMW M5. In conjunction with our
technology partner, the engineers have equipped the V8 TOPSTER with
special intake and exhaust camshafts. The cylinder heads have also been
fine-machined, the compression raised to 11.5 : 1 and the control unit
reprogrammed. To improve the exhaust gas flow, an
environmentally-friendly special steel high performance exhaust system
has been developed with twin chromed racing tailpipe trims in right and
In comparison with the M5, the power plant has had to be re-positioned
in the engine bay of the Z4 basic vehicle and the entire oil circuit
optimised, so it was necessary to modify the oil sump and oil pump.
Finally, the air flow was improved. By means of new intake pipes and 2
air filter boxes, the entire intake tract could be optimised. These
modifications have together resulted in the following performance
Power: 331 kW / 450 HP
Maximum torque: 520 Nm
0 - 100 km/h 4,5 seconds Top speed: 305 km/h
These figures are not only the result of
the new engine but also a perfect combination of high engine power and
optimally adapted power transmission. To match the power of the engine,
the drive train and rear axle were also modified. The rear axle, with a
gear ratio of 3.62 : 1, has a variable differential lock from 0 - 100 %
depending on the load of the V8 TOPSTER. In addition the AC Schnitzer
"Short Shift" is fitted.
Perfect retardation is provided by the AC Schnitzer high performance
brake kit. This uses larger brake disks of Ø 365 x 32 mm at the front
and Ø 328 x 20 mm at the rear in conjunction with special brake calipers
(2-piston on the front and single-piston floating caliper on the rear).
Even after several "hard brakings", the system achieves deceleration
values of 1 g and more.
In motorsport the correct set-up is often decisive for a victory or
podium place, and our development engineers place particularly great
importance on optimum suspension settings. In the V8 TOPSTER the driving
dynamics are decisively improved by the special development of a
9-position adjustable AC Schnitzer racing suspension. As well as
lowering by 35 mm in relation to its distant relation - the standard Z4
- the spring and damper rates have been substantially modified towards
more sports performance. In addition the wheel bearings and front and
rear control arms have been replaced.
To counter sideways body roll, AC Schnitzer developed anti-roll kits on
the front and rear axles. A further suspension highlight is the
aluminium strut brace which optimally prevents torsion in the vehicle
The AC Schnitzer V8 TOPSTER keeps contact with the asphalt through the
brand-new racing rims Type IV. The sporting yet elegant 5-spoke wheels
have particularly fine filigree work. The individual spokes which run
star-shaped from the pentagonal wheel centre to the polished bed
perfectly complement the avant-garde TOPSTER outfit. But the wheel and
tyre combination is not just an aesthetic highlight. With sizes 9.0J x
20" ET 18 with tyres 255/30 R 20 (front) and 11.0J x 20" offset 0 with
tyres 305/25 R 20 (rear), the TOPSTER can corner at speeds otherwise
reserved for a thoroughbred Touring Car.
Wheels of this size have to be accommodated somewhere. Just one reason
why the bodywork above all had to be adapted to the far higher demands
and widened by 13 cm overall.
Even at first glance, the reshaped bonnet of the AC Schnitzer V8 TOPSTER,
with its unmissable power bulge and large air outlet, already suggests
that beneath it sits a very powerful engine which needs maximum cooling
air flow, especially under full load.
Also a new development is the front skirt which gives the TOPSTER an
even lower look and considerably improves downforce on the front axle at
high speeds. Its large air inlet with integral grille ensures additional
cooling for the engine and front brakes, and gives the TOPSTER an
unmistakable facial expression. Last but not least, the xenon headlamps
integrated into the front skirt ensure that even at night, the driver
has excellent visibility.
To take into account the venting of the V8 engine, the new front side
walls contain large air vents which, with their 3 chrome ribs and
integrated flashers, are reminiscent of the deflectors on the AC
But not only at the front of the vehicle must the V8 TOPSTER have
adequate air exchange to develop its full potential. This principle
naturally also applies to the rear.
Consequently the striking side skirts house air ducts for the rear
brakes. The side skirts, which also give the TOPSTER an elongated look,
form the harmonious transition to the rear side walls and the monstrous
rear. The rear skirt accommodates not only an underfloor wing, but also
the complete double exhaust system made of stainless steel.
The specially developed roof, with its supporting function, further
reinforces the body of the V8 TOPSTER. With the TOP, the TOPSTER
develops a new, homogeneous body side line - similar to a coupé. The
integral rear roof wing in conjunction with the two-piece rear wing
mounted left and right on the boot, improves the downforce of the entire
In the development of the special accessory range for the BMW Z4, even
the initial studies of the TOPSTER could be considered. Similarities in
the aerodynamic packages available for the BMW Z4 and the V8 TOPSTER are
therefore deliberate and technically sensible.
The interior of the AC Schnitzer V8 TOPSTER is a combination of
developments in the AC Schnitzer range available for many BMW models,
and special one-off products. These include the racing bucket seats in
leather. The airbag sports steering wheel, gear lever gaiter and
handbrake cover are also provided in Alcantara with orange stitching.
Velours foot mats also with orange applications and the leather logo
round off the TOPSTER interior.
A carbon-fibre interior and chromed cover for the standard roll-over bar
and the aluminium accessories - comprising the pedal set, foot rests,
gear knob and handbrake handle - are however components of the standard
AC Schnitzer range for the Z4.
The AC Schnitzer V8 TOPSTER was developed as a technology showcase. In
the equipment level and form shown here, this concept car would cost
around € 185,000.00. Series production is not planned.
Technical Data - AC
Schnitzer V8 TOPSTER
Body: Basis BMW Z4
Engine: BMW V8 power plant S62 with
AC Schnitzer performance upgrade
Engine type: V8 four-valve engine
Capacity: 4941 cc
Bore: 94.0 mm
Stroke: 89.0 mm
Compression: 11.5 : 1
Nominal power: 331 kW / 450 HP at 6600 rpm
Max. torque: 520 Nm at 4100 rpm
Power transmission: Six-speed manual gearbox with AC Schnitzer Short
AC Schnitzer rear axle 3.62 : 1 with
variable differential lock 0 - 100 %
0 - 100 km/h: 4.5 s
0 - 200 km/h: 13.9 s
Maximum Speed: 305 km/h