It's the most important European motor show of 2011: the IAA in Frankfurt, which opens to the public on September 15, will showcase the latest technology from European and world car makers and suppliers.

There are always plenty of surprises revealed at the show, but here are the technical highlights we're already looking out for - starting with the big German car makers, who always aim to make the most noise at their home motor show.

BMW: i sub-brand launched with i3 electric city car and i8 hybrid performance car

Striking styling and 21st-century powertrains come together in the first two cars from BMW's i sub-brand, which will be seen for the first time in public at Frankfurt. They're sure to be stars of the show.

Mercedes-Benz: SLK 55 AMG with Cylinder Management and new B-class

Mercedes launches a new 5.5-litre normally aspirated V8 engine to replace its existing biturbo unit. The new M152 motor makes its debut in the SLK 55 AMG and uses AMG Cylinder Management to deactivate cylinders in low-load running, improving fuel economy and emissions performance.

The new B-class, which makes its debut at Frankfurt, is an important mass-market model for Mercedes-Benz and promises low-drag aerodynamics. Daimler has been developing its fuel cell vehicles using the B-class, so will there be a fuel cell option for the new car?

Audi: new V8 for S models with cylinder deactivation and active noise cancelling, plus urban concept

Audi unveils new S6, S7 and S8 models powered by newly-developed 4.0-litre TFSI V8 engines. In the S6 and S7 the new engine generates 420PS, while the S8 gets a 520PS version. All incorporate Audi's "cylinder on demand" technology which shuts down four cylinders when power demand is low, coupled with active noise cancellation and active main bearings to reduce NVH when running on four cylinders. Audi also officially reveals its urban concept.

Porsche: new 911 with lightweight body, active anti-roll and adaptive aerodynamics

Porsche's latest 911 features aluminium/steel construction which cuts weight, and has a variable geometry rear spoiler to reduce high-speed lift while minimising drag. Electro-mechanical power steering cuts power loss and saves fuel, and there's the option of an active anti-roll system which improves cornering performance.

VW: Up! city car with new three-cylinder engines

The big news from VW is the introduction of the Up! city car, which introduces a range of new three-cylinder engines. The Up! will be available with active emergency braking, a first for a car in this sector.

Toyota: Prius Plug-in Hybrid

Toyota's Prius Plug-In Hybrid makes its debut at Frankfurt. A compact lithium ion battery gives extended electric-only range and reduces fuel consumption and CO2 emissions to 128.4mpg and 49g/km of CO2 in the standard tests.

Ford: Evos concept previews 2012 C-Max Energy hybrid drivetrain

Ford's Evos concept presents a new design direction for the blue oval, and also previews the plug-in hybrid drivetrain with lithium ion battery which goes into production next year in the C-Max Energi. In the Evos, the operation of the powertrain is optimised using information from the driver's "personal cloud" of information, such as driving habits and appointments schedule. Ford claims the Evos has a 500-mile range, more than any other plug-in hybrid.

Citroen: DS5 introduces Hybrid4 diesel hybrid system

Citroen gives the DS5 its European premiere, and with it comes the Hybrid4 diesel-electric hybrid technology which combines four-wheel drive and up to 200PS with electric-only operation for city use.

Peugeot: HX1 hybrid concept and 508RXH production car

Peugeot is making the most of the Hybrid4 system, launching a 508RXH production car at Frankfurt alongside the HX1 concept (above). HX1 flies in the face of conventional MPV design, putting space for six occupants under a low roof, within an estate-like profile which features active aerodynamics.

Infiniti: FX Vettel concept

Inifiniti will display this FX-based concept vehicle, developed with brand ambassador Sebastian Vettel - who has an Infiniti FX as a road car. Externally the concept has a wealth of carbon fibre parts. More carbon is expected inside, together with a multi-function steering wheel. No information has been released about the concept's powertrain, but it may use to 420PS Infiniti M56 V8 engine.

Ferrari: 458 Spider is the first mid-engined car with a retractable hard top roof

Ferrari launches its 458 Spider at Frankfurt, and the key technical interest is in the new roof - a folding hard top, for the first time on a mid-engined car.

Alfa 4C concept: closer to production

Alfa Romeo's 4C Concept makes a reappearance, this time swapping its original matt orange for a 'liquid silver' finish. Technical details are closer to confirmation, with the kerb weight expected to be around 850kg and an output of around 215PS from a turbocharged 1750 four-cylinder engine.

Fiat: third-generation Panda introduces normally-aspirated TwinAir engine

Fiat's third-generation Panda looks much the same as the outgoing model, but under the skin there are interesting technical developments. The two-cylinder TwinAir engine will be available both in its existing 85PS turbo form and in a new normally-aspirated 65PS guise, and there is a new 1.3-litre Multijet 2 diesel.

Land Rover: Defender DC100 concept opens debate about 2015 Defender production model

While the styling of Land Rover's Defender DC100 concept is bound to polarise opinion, the real interest lies in the technical details of this concept vehicle's construction and drivetrain - which must have extreme strength, utility and the go-anywhere ability for which the Defender is famed but which must also cater for a changing marketplace. The solutions in this concept should give the first pointers to the technical features of the 2015 Defender, which Land Rover has confirmed for production.

Jaguar: C-X16 points to future small sports car

Jaguar remains tight-lipped about its C-X16 concept, which will be revealed for the first time at Frankfurt. So far only this sketch has been released, and there are no official details of the car. It will be interesting to see if Jaguar can use its aluminium architecture on what will be a smaller, lower-priced car than the existing XKR. The choice of powertrain will be interesting too: four-cylinder engines may be available in the eventual production car, but expect a more exciting choice of power unit for the concept car.

Honda: ninth-generation Civic aims for refinement and ride quality improvements

Honda will unveil a new-generation Civic at Frankfurt. The company is claiming that detail suspension work has produced a "two generation" improvement in ride and refinement, and while we won't be able to judge that at the show we should at least get to see the rest of the car: so far this is the only undisguised image Honda has released.

Opel Vauxhall:

The Astra GTC, production-ready Ampera and a fleet of new Ecoflex models will all be on show, and Opel Vauxhall promises "the surprise debut of an experimental car that will emphasise the company’s passion for driver-focused vehicles".

Mazda: CX-5 introduces Skyactiv technologies

Mazda's CX-5 makes its debut at the Frankfurt show, and brings with it a range of weight reduction and efficiency enhancement technologies which Mazda calls Skyactiv.

Other key debuts: the best of the rest at Frankfurt 2011

• Bentley: Continental GTC, drophead version of latest Continental
• Kia: four-door sports saloon concept
• Seat: revised and upgraded Exeo

• Ssangyong: XIV 1 SUV concept
• Subaru: XV compact SUV production car and BRZ Prologue technology demonstrator which previews new Boxer-engined sports car