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Lotus Engineering and Continental Division Powertrain Present Results of “Low CO2” Mild-Hybrid Project

The Low CO2 concept uses engine downsizing and a mild hybrid drive to reduce CO2 emissions some 15% from a stock version of the same Astra vehicle.

Lotus Engineering, the automotive consultancy division of Lotus, and Continental Division Powertrain have presented the results of their “Low CO2” research collaboration. The primary objective of the Low CO2 project was to deliver greatly reduced CO2 emissions while maintaining an engaging driving experience from an affordable set of technologies. The solution employs an integrated set of powertrain systems within a downsized overall package.

The Low CO2 vehicle concept is demonstrated in an Opel Astra, and produces 149 g/km CO2—a reduction of 15% against the naturally aspirated 1.8-liter 4-cylinder engine version of the same vehicle.

Lotus brought to the project its powertrain design, development, testing and validation capabilities, with specific expertise in engine downsizing and systems integration. Continental Division Powertrain supplied its experience in powertrain management and control systems, especially in the areas of direct fuel injection systems, hybrid drives, energy management, emission after-treatment and a number of new technologies.

The Low CO2 Astra features:

  • A Lotus Engineering-designed pressure-charged three-cylinder 1.5-liter gasoline engine;

  • An innovative integrated exhaust manifold design;

  • Centrally-mounted injectors;

  • Cam profile switching for variable lift and timing;

  • A high-pressure fuel pump; and

  • A mild hybrid drive with supercapacitors for energy storage.

The Low CO2 engine uses a new advanced cylinder head design featuring an integrated exhaust manifold. Click to enlarge.

The engine exploits the findings of the HOTFIRE (Homogeneous and Throttleless for Fuel efficiency with Reduced Emissions) project, a three-year research program led by Lotus Engineering and also including Siemens VDO (since acquired by Continental), Loughborough University and University College London.

HOTFIRE, which started in October 2004, was based at Loughborough University to explore a permanent homogeneous charge direct injection strategy through a fully variable valve train system with the use of centrally-mounted injectors.

The cylinders in the engine have a bore of 88mm and a stroke of 82mm. Compression ratio is 10.2:1. Continental Division Powertrain’s single cylinder fuel pump is driven directly from the tri-lobe cam on the exhaust camshaft. Fuel pump pressure is 200 bar. Both fuel pump and water pump are electric, providing fuel savings of up to 2%.

The fuel injectors are affordable, 200 bar, solenoid, direct injection centrally mounted injectors provided by Continental Division Powertrain.

Lotus Engineering designed and developed a new advanced cylinder head design featuring an integrated exhaust manifold. The production-ready technology can significantly reduce manufacturing costs, emissions and weight on most gasoline-engined passenger vehicles, according to Lotus. An integrated exhaust manifold has potential to:

  • Reduce parts count: 35% fewer components resulting in lower inventory, production, logistics and aftermarket costs;

  • Reduce weight: total system mass reduction of 20% resulting from elimination of separate exhaust manifold; and

  • Improve durability.

Lotus Engineering’s Cam Profile Switching system incorporates lobed tappets that vary valve lift and timing. The system is produced under licence by INA and features in Porsche products in its ‘VarioCam Plus’ system.

Maximum power from the engine is 159 hp (118 kW) @ 5,000 rpm, with maximum torque of 240 Nm (177 lb-ft) @ 2,500-4,000 rpm. The mild hybrid motor, which is placed between the engine and the transmission, delivers 12 kW of output. 60V supercapacitors provide the energy storage for the mild hybrid system.




this is a bit of a problem i think. if the best they can do with a little 1.5l is 149 g/km, how is it going to be possible to meet the EU's 125 g/km target?
this engine is not short on technology either. how much would this add to oem production costs?
on the other hand, i think that part of the problem is manufacturer resistance to new technologies. is there a legitimate engineering/technical reason why direct injection is not on every gas car? if it were standard equipment (the way EFI is now, when it was once more of a luxury oprtion) economies of scale would made the price difference negligible.


Not a huge improvement in fuel economy. What about the rest of the drivetrain? Transmission? Tires?


"this is a bit of a problem i think. if the best they can do with a little 1.5l is 149 g/km, how is it going to be possible to meet the EU's 125 g/km target?"

not a problem. polo bluemotion and mini cooper D already emit less than 125g/km, with conventional diesel engines.

John Baldwin

if you now run the vehicle on compressed natural gas, should meat the 125 g/km target. No problem.

John Baldwin

if you now run the vehicle on compressed natural gas, should beat the 125 g/km target. There are 800 NGV stations in Germany, Opel make good NGVs like the Zafira.

For UK, there is a problem.

John Baldwin

if you now run the vehicle on compressed natural gas, should beat the 125 g/km target. There are 800 NGV stations in Germany, Opel make good NGVs like the Zafira.

For UK, there is a problem.


If the only thing that is permitted to be sold is little cars like the Mini Diesel and Polo Bluemotion, then the fleet turnover will hit zero.

People will opt to keep their existing vehicles rather than be forced into smaller less suitable cars.

This would bring the large auto manufacturers to their knees and progress would halt. We'd be stuck with the existing fleet for as long as they can be maintained roadworthy.

If classic cars are anything to go by that can be a long time.



Mid sized cars like the Meganne (diesel) can hit <= 120 gms/km - without hybridization.

The problem is they are diesel and not particularly cheap.

Diesel is fine for open spaces, but a bit polluting for city use - but it is the way Europe has chosen.

As this car is a 3 cylinder, I wonder what it sounds like.

Also, I wonder how much energy the caps can absorb - i.e. stopping from what speed to zero.

A supercap stop/start system could be very good for city use - it is the opposite of a PHEV - e drive is only used for restarting the engine.

At least they haven't but a silly PV panel on the roof.


The improvement is rather desapointing, not sure it is worth the effort, I think automaker should rather focus in implementing more advanced solutions that can provide more dramatic improvment like the one develloped in france by EMC-5.

Look at that's the future of gazoline engine along with otto-diesel from mercedes


You all seem disappointed, but I'm not sure why.

The engine develops something like 30hp more than the engine it's being compared with, even without the 16hp electric boost. Downsizing the 1.5 to a 1.2 should easily bring it within the required numbers, provided that the technology scales down.


Err, isn't this a GM company? How can it be any good?


The problem of downsizing further is that the lateral friction on the cylinder wall becomes a serious problem, that's where the design of EMC-5 beat other design thanks to their specific design there is no lateral pressure on the cylinder wall so you can downsize as much as you want.


Sorry the right adress is

The next revolution in gazoline engine.



I have a 3 cylinder car just now I can confirm that they sound great.

The offbeat sound they produce is much better than the drone of a four-banger.

I'd rather have a 3,6 or 8 cylinder car than a 4 cylinder car (boxter engine excepted)



The music of the engine is clearly futile discussion and oof debate here when it comes to sustainable transportation, an electric car will emit no noise at all, but you can still download the sounds of a ferrari on your i.pod and listen it when you drive, result garanteed and you won't annoy people around as so many people do when then customize their exhaust just for the fun of making noise.


I think that I might like the turbine whine of an electric car. I would imagine that the road noise for people outside would be less. Imagine all the freeway walls that they have had to build in the U.S. Building more might not be necessary if vehicles were quiet.


The noise of engine is unimportant until you try to get people to buy the vehicle.

From a strict efficiency point of view, it makes no difference, but an efficient car that no-one will buy is a wasted effort.

And while you could produce any noise you like from a sound system, it has a whiff of artificiality - if, as you suggested you had an electric car that sounded like a Ferrari and looked like a G-Wiz, you would make a bad image worse.
By all means, use technology to solve noise problems, but just don't overdo it.
As an aside, we may need to force cars to make noise if they become too quiet - for safety reasons (but that is another story).

What we want are efficient cars that people can afford and are willing to buy in large numbers.
If you don't get the numbers, you won't have solved the problem - you will have salved a few wealthy people's consciences and kept some engineers employed.


I think that the key points to this car are "production-ready" and "low-cost."
Sure, it's only a 15% improvement on the 1.8l Astra (which is the engine that Saturn uses in the North American Astra), but it's 15% that can be implemented in the short term with minimal R&D and tooling costs.

Nothing wrong with that.

Keep in mind that the engine that this is being compared to already has variable valve timing on both cams, and an exhaust manifold that is highly optimized. It's not like they are getting a 15% improvement on an outdated design; the 1.8 in the Astra is a state of the art engine that is as good or better than current 1.8's from Toyota, Nissan, VW, or anyone else.



I don't see your problem with artificially made sounds for a noiseless car, in a america everything is artificial, artificial food, artificial tastes and smells, artificial cities, artificial material, fake, america has lost the taste (and the sense) of reality in almost everything, so ?

hampden wireless

That is 15% on a car that uses no exotic batteries and possibly a lower cost then many of the regular engine parts it replaces. The cost of this type of car could be less then GM's very mild hybrids with a greater payback.

I like it.



Highway noise walls are to counteract "tireslap" not engines.

At highway speeds the noise from the tires far exceeds that of the engine...with the exception of Treehugger's super-sized exhaust antagonists.

Ferrari sound on an iPod? I hope you use a lossless compression, have a great sound system, and some type of intelligent DSP or it will just sound like a video game - one that is being played too loudly.


I will not argue the point, because I am not an expert, but the freeway near here seems to generate a lot more engine noise than tire noise. It is a small point, but one worth mentioning.


Around September 2007, Siemens VDO Group Vice President Dr. Klaus Egger stated that "The cooperation with our partner, Lotus Engineering, shows once again, that there is still a lot of potential for further innovation and development within the internal combustion engine. The combination of direct injection and turbo charging means noticeably better fuel economy and lower CO2 emissions for the Gasoline engine, without compromising driving fun. With our advanced expertise in low CO2 know-how we see clear benefits for our customers and will further strengthen and improve our role as systems integration experts."
I agree there is a lot more potential for improved design of the reciprocating engine. In this case it is Co2 reduction. However the turbo charger aspect is being downplayed being variously described as a turbocompressor and now "pressure charged". Initially I was amazed to read this engine had 177 Lbs-ft of torque, I would have expected only about 128 Lbs-ft from a normally aspirated 3 cyl 1.5L engine with 88mm dia pistons. Then I reread more closely and noticed the pressure charged reference which takes some of the bloom off the rose. However achieving useful Co2 reductions with direct injection is a good way for Lotus to go now that Porsche is having their problems with city congestion charges.
Meanwhile back at the farm, is 'pressure charged' going to be newspeak for turbochargers ?

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