"special aerodynamic effect" (on picture) "requiring one kilowatt less of propulsion power at a speed of 160 km/h".

That sounds like a bit farfetched idea. They should have also calculated how much it saves while driving at 250 hm/h while they're at it. I agree that any improvement is good to take though but there has to be a better and cheaper way. See what Renault did on the eco Logan for instance.

This sounds like a winner if it goes beyond concept. The small motor could be bigger and the engine output does not need to be so high, but 36 mpg sounds good.

The electric motor is attached to the automatic transmission, by the looks of it in-between the torque converter and the first reduction stage. Its speed is therefore very nearly that of the engine once the TC freewheels. The engine, which is already used in the 1 series, features a dual turbo system that minimizes turbo lag and delivers high static torque at very low RPM. Since the transmission has eight gears, both engine and motor can always operate at high efficiency at all vehicle speeds. This explains why the fuel consumption in the NEDC is quite good for a vehicle of this size and weight.

However, with this much torque under the hood, actual drivers will be sorely tempted to accelerate much harder and drive much faster than the NEDC simulates - substantially increasing the fun-to-drive factor but also real-world fuel consumption. The hubcap gimmick cannot hide the fact that this is a heavy SUV with the overall aerodynamics of a brick.

Moreover, an eight-speed AT is expensive, as is fitting dual turbos to a diesel engine. The electric motor, power electronics, Li-ion battery, dual electric grids and control software also cost a pretty penny. In its present guise, this approach will not scale to vehicles built in high volume. In the US market, emissions regs, low fuel taxes, exchange rate and consumer price sensitivity all mitigate strongly against a diesel mild hybrid quite this fancy in this vehicle segment.

As for the solar panel, assume a panel-to-wheels efficiency of 0.7 incl. conversion stages, intermediate storage in the battery, the motor and the mechanical transmission elements. If the solar panel really delivers 1 kWh per day - i.e. a bright sunny day & a clean panel - that translates to 2.5MJ at the wheels. Assuming an average efficiency of 25% for the diesel engine plus transmission, it would consume roughly 250ml to deliver the same amount of work to the wheels. In Germany, that's worth about EUR 0.30 at the pump.

Unfortunately, the panel will not deliver a full kWh on every day of the year. The yield will be far lower in winter and in poor weather. It will also be far lower if the panel is not frequently cleaned, it has been damaged by a car wash or, if the car is not parked in full exposure to the sun - which greatly increases initial A/C load in summer, more than negating the benefit. In the real world, you'll therefore be lucky to average 0.5kWh per day. That means annual savings at the pump in high-tax Germany may amount to no more than EUR 50.

Ergo, a solar panel on a car roof will never pay for itself. It is just marketing gimmick for trade shows.

"It is the first diesel in the world with a specific power output of more than 100 bhp per liter of capacity."

first production diesel, perhaps. however the audi R10 produces 650bhp (restricted) from a 5.5L engine.

am i missing something?
2008 Chrysler/Dodge 3.8L V6 is 197bhp petrol/gas (147 kW)
2007 BMW 2.0L 4-cyl diesel 204bhp

What a bunch of whiny nitpicking losers!

Agreed the solar panel won't pay for itself at today's PV or fuel prices.

However I think some buyers would still pick it as an option for when they are out camping. 1 kWh per day is a lot of television and microwaving without the need for a smelly/noisy generator!

This is listed as a concept so there is no guarantee of production. But it would be nice to see four cylinder turbos in lighter vehicles with parallel hybrid configurations.

Built-in solar generally will have market appeal even if the cost/energy remains out of balance. RV and marine enthusiasts have topped house batteries for years with relatively small panels. If Clett's estimate for a lighter vehicle holds true and a three day camping trip yields a 15 mile all-electric travel equivalent, then 45mpg (Prius) @ US$5.00 x.33 = $1.81 or .60/day x 300 (in sunny climes) $180.00 annual. A gimmick - yes. But so is the Prius energy display showing regen charging of batteries. People like the idea of "free" energy even when the EE and MEs tell 'em it's not really free.

Interesting and smart comments on the cost/benefit of the roof mounted solar panel. However, I think BMW nailed it from a behavioural economics point of view when they made their decisions about which features or benefits to build into this concept.

Do most auto buyers rationally consider cost/benefit ratios when purchasing a car? I don't, that's for sure. I set my maximum price and then find a cool car that meets my lifestyle requirements - in my case that's a small wagon that can haul a decent amount of crap and is fuel efficient.

I have a hunch that a solar panel is a great sounding feature for many consumers, and its perceived benefits go far beyond savings at the pump. The comments about solar charging of accessories for camping are spot-on. Potential buyers of this kind of vehicle will love the panel, even though I doubt very many drivers of a BMW SUV would ever go camping.

A couple of comments from an EE/ Car enthusiast
1. Whole concept is wrong, this is a concept vehicle right? Needs an engine only big enough to maintain steady max design velocity (mph or kph)on level road. Electric MG big enough to compensate for needed acceleration and hills. This would dictate a much smaller ICE and a much larger electric MG.
2. Batteries should be state of the art in a concept vehicle and should have enough capacity to provide storage for all stopping/slowing and power for hills and acceleration. This design does neither.
3. Price differential between gas/diesel fuel makes the added efficiency of the diesel mute.
4. The solar is a good idea. Many Prius owners have found severe problems when parking for extended periods such as airports and losing battery charge due to all the electronics. The solar would not provide much for the car motion but would keep the batteries charged for period of inactivity. However, on my Prius I plan to just buy a suction cup plug in type solar charger to put in the window when I need it
5. All in all I think this is not as good a design as the Ford Escape hybrid. I own a 2008 Pruis which also is not as good a design as the Ford, but it meets my needs better. Both need better, larger, batteries though and some changes to the computer programming. With the right batteries and programming the Escape can get 45-50 mpg easily. It can be pushed way above that with high priced batteries.
6. While BMW has great engineers, they argue with themselves too much, and never settle down to a final design. They even continually change things in a given model year on a production unit. This is why a friend of mine who has enough BMW stock to qualify for a "free" BMW each year chooses something else. I do own a BMW powered vehicle that I would like to get one of the 2.0/204hp engines to replace.