Theres lots of forms of racing that arent as appealing as LMP1, so I dont see a reason to bash the DPs which put on a pretty good show and if given carbon brakes and better tires (Continental promises to step up their game) arent as slow as many may think. They would probably be right at LMPC pace. Part of the reason they're not as fast as most prototypes is that they're built to be stronger and cheaper to fix then a prototype with all these winglets and fragile parts.
P1 is going away from the merged series next year because the WEC is a more attractive option for manufacturers. Why let two or three privateer P1 cars dominate the show next year when you can have a dozen DPs, a few P2s and a delta wing go at it for overall honors in the new series?
The DP's will need a lot more than carbon brakes and better tires to be competitive with LMP2s. P1 is going away in N.A. because that's GA's way of trying to play their hand. They think their DP should be the top class, and there's no way to bring that up to speed with an LMP1. You can make reasons all you want, but the truth is GA doesn't really want to change all that much. "The Future" isn't as bright as you think it is. It's going to take a while if it ever succeeds. They had an opportunity to include their huge events in the ACO FIA series, but they didn't. The only thing they'll maintain is GTE and possibly LMP2. I wouldn't even bet on that...
Anyway, as far as the BMW Z4 GTE is concerned-
http://www.bmw-motorsport.com/en/news/current-news/2013/02/alms_bmw_z4_gte_launch.html
http://auto-racing.speedtv.com/article/alms-bmw-launches-z4-gte they have a good amount of pictures from the launch.
http://www.motorsport.com/alms/news/bmw-z4-gte-takes-center-stage-with-team-rll-in-daytona/ has technical specifications
Length: 4,395mm (excl. rear wing)
Width: 2,010mm
Height: 1,205mm (depending on set-up)
Weight: 1,245kg (according to ACO regulations)
Tank capacity: 110 litres (according to IMSA classification)
Chassis/body: Steel body with welded safety cell
Transmission: six-speed sequential sport transmission, operated via shifting paddles mounted on the steering wheel, multiple ZF Sachs clutch
Front axle: McPherson axle with pushrods and wishbone, additionally with adjustable shock absorbers, H&R coil springs
Rear axle: Longitudinal links with wishbone, adjustable shock absorbers, H&R coil springs
Brake system: hydraulic dual circuit brake; monobloc multi-piston light alloy brake callipers, innver-vented steel brake discs, seamless brake balance adjustment (front and rear) by the driver
Wheels: BBS forged aluminum wheels, front axle: 12,5x18“, rear axle: 13x18“
Tyres: Michelin, front axle: 300-680-18, rear axle: 310-710-18
Engine type: Eight-cylinder, V-configuration, four valves per cylinder, mandatory air restrictor (2x29.4mm)
Capacity: 4,400cc
Max. output: approx. 480bhp (with mandatory air restrictor)
Max. torque: approx. 480Nm
Cylinder block: Aluminum cylinder block construction
Engine management: BMW Motorsport ECU 408, without fuses, central display