I always thought that the Z4 was based off of the E90/1/2/3 platform?

Nope, based on the E46 platform. Although some suspension components were borrowed from the E90...

The Z4 is an interesting mix and not as clear cut as the X3 (which is E46 platform & parts through & through). Its suspension is part E90, its electrics part E46 and part of a new rover platform BMW was developing to share between BMW's & Rovers at the time. The Z4 is the only car that uses this platform today...

Also of note, the Z3 was based on the archaic E36 platform, despite it being launched around the same time as the E46...

Also interesting to note is (I believe) the fact that while the Z3 was based off the E36, it had I believe a rear axis and more parts from the E30 3er (!!!)

If there is a car in today's BMW product line up that just shouts the emotion and dynasim of the brand then it has to be the BMW Z4.

A radical departure from the previous Z3 with a modern interpretations of classic roadsters - long bonnet , and short rear overhang.
Classic proportions that stand out today.

In the next generation of Z4 a car that looks as dynamic and purposeful today as it did on it's 2002 release - seen from a distance even before the facelift introduction the car looks stunning - It's that low deck feeling and the looks that you are so close to the road sitting only a few inches from the asphalt for that ultimate seat of your pants ride.

Whilst the Z4 has not performed as well in several key markets due to it's looks and style - This segment is mainly bought by female demographic - whilst the SLK , Audi TT b42006 and Porsche Boxster have the attraction to interest the female demographic - The Z4 has done the opposite with the great percentage of owners being male .

Now with the prototypes on the street for the next generation - There are several areas where BMW are keeping the same formula yet adding something new to increase it's overall appeal.

Whilst the Hardtop come cabrio SLK has been extremely popular with an overall market lead thanks to it's duality, BMW having worked on finding the right solution for their cabrio's beginning with the 3-piece folding top on the 3er E93 will adapt the system for the next Z4 Roadster.

The next Z4 Roadster will use a folding hardtop manufactured from lightweight steel and will be a two-piece affair folding neatly underneath a small deck - When in stored form the two-piece roof becomes compact splitting and folding on top of each segment . The addition of side windows incorporates an allround view rather than the claustrophobic view of the current Z4 Roadster.

The chassis which part comes from the E90 offers additional areas to combat weight distribution problems . The entire front end and front suspension are entirely manufactured from aluminium - With the engine block constructed using magnesium. The rear of the car is again alumnium with aluminium heavily featured in the rear suspension . structural safety is taken care of by injection of sealant into the car which hardens providing excellent structural safety . Pop-up roll bars are more than just design elements and again will contribute to roll over safety alongside the usual compliment of airbags , seatbelt pretentioners , windscreen rails and BMW's upcoming safety warning system.

The design of the current car has been both mixed with some in favour and some against especially when the claim the design is too much in motion to be appreciated.
Whilst the current car is definiteley kinetic from the Z style slashes to the lift on the rear wheel arches . The new Z4 will inherit some kinetic form but be less pronounced.

The front of the car uses slimline snake-eye slits surrounding a wider kidney grille the twin eye BMW look of the headlights are set further back into the front of the car with the perspex cover revealing a set back sports car look.
Intakes on each side of the car form additional area for the airflow to the brakes. From how the front light slits sit at the front as the triangular shape forms onto the bodywork underneath the lights this forms a small ledge where the headlight washers rest.

The distinctive Z slash is less prominent as this now begins from the rear slashing the bodywork - a faired in M3 style side intake is added with an LED this bar now features the insignia Z4 after the indicator lights the BMW insignia is now relocated to just the two roundels on the exterior.
The rear arches flair out similar to the CS Concept , The purpose is to continue the dynamism by increasing the athletic tone of the car.
Round the rear the "Cobra" like lamps have been replaced with smaller CS / E82 style slits as these connect the rear deck to the bootlid - Like the 6er where every form and line connects with the bootlid the same idea is carried over whilst the bootlid is more flatter and compressed than the E63 look.
The swept back , low driving close-to -the-road look remains as does the elongated hood and short rear deck.

The interior contines the dynamic apperance of the current car with the flat stylish dashboard - idrive will become faired in like the X5 and X6 models as the flat surface slopes , The central console is angle towards the driver - classic BMW style with one side of the dashboard dividing the passenger - similar to the CS concept this will incorporate idrive and the gearbox options.
The air con vents become thin strips in the center of the dash which incorporates the heating controls and idrive quick keys.

Of course where the next Z4 ends up determines on the next course of action from the rivals - The current SLK is contrived and is nothing classy or elegant as the first SLK which had the looks instead of being a poor looking SLR for those on a budget.

The current TT Roadster looks right because it is an excellent interpretation of the original - keep the form but update it - looks superb. And the Boxster? meh I can understand the reason not to mess with success but how are they going to conceive the next one?

Nice and all, but we're more interested in this upcoming M model....tell us about that instead

M6 CSL??

thanks scott can i ask you something because im planning to buy a z4m coupe any news about the 2008 model? and will they make a coupe version of the new z4 thanks again

Arnold

I hope, they will not produce the Z4 with a folding hardtop! Roadster look so much better with Softtops, in my opinion...

Thanx, Scott, for much Info.
as far as i know new Z4 get both: folding cloth and metal roof.
It´s Buyers choice .

I really hope, you're right...

How about losing some weight ?!
That would interest enthusiasts.