BMW To Introduce New Diesel Mild Hybrid Concept in Geneva
22 February 2008
|The elements of the BMW Vision EfficientDynamics concept. Click to enlarge.|
BMW will introduce the concept BMW Vision EfficientDynamics at the upcoming Geneva Motor Show (6-16 March)—the company’s first combination of a 4-cylinder diesel engine with BMW ActiveHybrid Technology in a large Sports Activity Vehicle.
Based on a BMW X5, the diesel mild hybrid concept delivers average fuel consumption of 6.5 liters per 100 kilometers (36 mpg US) in the EU test cycle and a CO2 emission level of 172 grams per kilometer. Acceleration from 0-100 kph is 8.9 seconds.
The 2.0 liter 4-cylinder diesel engine with Variable Twin Turbo, third-generation common rail injection and all-aluminum gearbox housing delivers 150 kW/204 bhp and generates a maximum torque of 400 Nm (295 lb-ft) between 2,000 and 2,250 rpm. It is the first diesel in the world with a specific power output of more than 100 bhp per liter of capacity. The motor/generator in the mild hybrid system contributes 15 kW and maximum torque of 210 Nm (155 lb-ft) to vehicle acceleration. The total output of the vehicle is 165 kW.
The hybrid module is based on technology developed as part of the hybrid co-operation between BMW and Daimler that goes beyond their partnership with GM on the two-mode system. (Earlier post.) BMW has also introduced a concept based on the full hybrid two-mode system. (Earlier post.)
The concept uses two parallel vehicle power systems. In addition to the conventional 12 volt system supplied by the AGM starter battery there is also an 120 volt system which is fed by electrical power from the generator and a new lithium-ion battery pack.
The high-voltage network and the Li-ion battery can support ancillary systems such as ventilation and air conditioning when the engine is switched off at idle or stop.
The Vision EfficientDynamics concept is fitted with a new 8-speed automatic transmission developed jointly by BMW and ZF Getriebe GmbH. Presented at Geneva for the first time and ready for serial production use, this 8-speed automatic transmission makes an additional contribution to reducing fuel consumption and exhaust emissions with its direct connection to the engine and minimized torque-converter slip.
The concept car also features a solar roof which acts as an additional energy source for the vehicle power supply which is independent of the engine. High-power solar cells covering a surface area of some 1.0 square meters generate a maximum energy of one kilowatt hour for consumers inside and outside the vehicle.
This enables pre-heating of the gear oil, thereby shortening the inefficient warm-up phase. Direct energy supply is possible during standstill for ventilation or for operating a cool box, audio equipment, a mobile phone charger or for charging the vehicle battery.
An innovative wheel rim design makes an additional contribution to reducing fuel consumption, by requiring one kilowatt less of propulsion power at a speed of 160 km/h. The aerodynamic shaping of the spokes reduces rim ventilation. This has a positive impact on the aerodynamic properties of the vehicle.
Hmm... a one-square meter solar root, delivering energy of one kWh over it's lifetime (10 years)? That would be pretty lame... I guess this should read a peak power of 1 kW (noon on the equator, when the sun is in the zenith).
Now, around here (central europe), that would mean about ~0,7 kW at noon in summer - in a garage that would be enough to maintain lubricant & cylinder head temperatures above 60 °C (not that you'd have sun there). On the street, with constant air circulation, that power would probably only maintain 35-45°C - still enough to minimize the cold-cranking (engine start) emissions of unburned HC - just like the CHSS does since about 5 years (which is much more cost effective, and also works in the dark and parking spaces with a roof.
Having that said, (and as indicated in the german article) it's extremely unlikely that such a gimmick as a solar roof will make it into a production car.
Other than that - this is again proof, that a brick on wheels cann't really be made efficient. 172g/km is still much better (-20%) than the current X5 (214 - 286 g/km) but still not below the minimal 160 g/km which was supposed to be realistic by 2008 by german car manufacturers. Why not put this drivetrain in a more aerodynamic body, like the normal BMW cars?
Posted by: realarms | 22 February 2008 at 05:25 AM
"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.
Posted by: Francois | 22 February 2008 at 06:02 AM
1 m2 of efficient solar panels would yield about 200 watts peak power.
The 1kWh they claim is the amount of energy that the panel could provide under optimal conditions over 1 sunny day in the summer.
(The average incident insolation for the whole USA over the year is about 5 kWh per m2 per day for a flat panel at latitude - multiply that by 20% for solar cell efficiency).
1 kWh is enough for about 4 - 5 miles electric-only driving range in a smaller (eg Prius size) vehicle.
Posted by: clett | 22 February 2008 at 06:03 AM
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.
Posted by: sjc | 22 February 2008 at 08:07 AM
Hmmm, Autoweek was reporting it as a 3.0L turbo diesel combined with hybrid gear.
Posted by: Patrick | 22 February 2008 at 08:11 AM
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.
Posted by: Rafael Seidl | 22 February 2008 at 08:36 AM
Nice concept on the solar roof but what happens when it snows? The battery still needs to support the full starting load at cold temps with no heating of the transmission fluid. Solar roof can only be an aux power source to improve efficiency.
Posted by: Neil | 22 February 2008 at 08:54 AM
"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.
Posted by: eric | 22 February 2008 at 11:55 AM
Rafael -- As for the solar panel -- you forgot
to mention that it will be far less efficient
at night!! LOL
Posted by: JJ | 22 February 2008 at 01:12 PM
am i missing something?
2008 Chrysler/Dodge 3.8L V6 is 197bhp petrol/gas (147 kW)
2007 BMW 2.0L 4-cyl diesel 204bhp
Posted by: | 22 February 2008 at 01:43 PM
@ JJ -
the 1kWh assumes 5-6 hours of exposure to bright sunlight at temperate latitudes during the day. Your comment didn't really add anything to the discussion.
Posted by: Rafael Seidl | 22 February 2008 at 02:12 PM
What a bunch of whiny nitpicking losers!
Posted by: LOL | 22 February 2008 at 04:50 PM
wow, guess that makes you the big man on campus eh LOL, an anonymous insult randonly thrown into a serious discussion. how tiny is your dick that you feel the need to make these remarks?
Posted by: gary owen | 23 February 2008 at 02:57 AM
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!
Posted by: clett | 23 February 2008 at 05:39 AM
will BMW produce a version that runs on hydrogen?
Posted by: John Baldwin | 23 February 2008 at 09:24 AM
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.
Posted by: gr | 23 February 2008 at 10:16 AM
This vehicle follows the pack with twice the engine required @ 160klm, for dismal economy figures , well we don't need that either.
Certainly increases Japanese economy slanted hybrids specification and philosophy stand out.
Like so much these days, people want to appear green and cuddly without compromising on unnecessary luxuries.
At this rate global reductions, EU seeing a 26% increase since 1990,are out the window.
These luxury makers might consider building and marketing with view to earning respect.
Posted by: Arnold | 23 February 2008 at 03:42 PM
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.
Posted by: jvp | 24 February 2008 at 11:36 AM
I don't think the solar panel was meant to provide power for locomotion, but for small ancillary devices, like media players and ventilation when parked, etc.
Posted by: damien | 24 February 2008 at 09:27 PM
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.
Posted by: GElightbulb | 12 April 2008 at 07:26 AM