There are only two ways to reduce emissions when driving a vehicle.

1.  Minimize the fuel consumption.
2.  Improve the combustion process.

1. Minimize consumption.

A significant reduction in fuel consumption of the new Hydrostatic Powertrain with Energy Storage is obtained through:

a.   Operating the engine only at constant power and speed.

The constant operating conditions allow for a highly optimized combustion process. No compromising operating profile is required to minimize the fuel consumption and emissions. Current engines have their highest efficiency at 2100-2400 rpm and nearly full power. The consumption can double under the more commonly used low power  (1/10) and high rpm conditions.

b.   The Hydraulic Free-piston Engine.

The 2-stroke Diesel engine has no crankshaft and valve mechanism and therefore very little frictional losses – about half of current engines. The combustion chamber is very compact and its small wall area extracts only little heat.

c.   Recuperation of the entire braking energy.

The wheelmotors are powerful enough to save all the energy typically wasted during braking. The accumulator can store the energy very fast. Other systems do not allow a comparable function for weight and cost reasons.

2. Improve combustion.

Significant less fuel is used in a cleaner combustion process. The improvements are based on a new fuel injection system, consisting of:

d.    Peripheral micro-slot injection.

Four times the number of nozzles (micro slots) of a quarter size inject the fuel from the cylinder wall into the chamber and obtain a noticeably better distribution of a finer fuel spray. Also, the undesirable impingement of fuel spray against the wall is noticeably reduced. A significantly improved air/fuel mixture is reached as needed for a very low polluting HCCI combustion.

e.   Ultra high injection pressure.

The nearly doubling of the injection pressure to 50,000 psi and the small micro-slots result in significantly finer fuel spray to further improve the air/fuel mixture for a homogeneous combustion.

It is expected that both factors will result in a Near-HCCI combustion (Homogeneous Charge Compression Ignition). This combustion has proven to be nearly free of toxic emissions (NOx, soot), but has been reached with conventional engines only in test labs and under very restricted conditions.

2. Comparison with electric cars.

Current studies show that electric vehicles release up to 65% less carbon than hybrids with 50 mpg, when the electricity they use was taken into account.  (San Francisco Electric Vehicle Association)  Meaning, the 170 mpg INGOCAR has a noticeably smaller carbon footprint than the best electric car (145 mpg).

The new fuel injection system of the free-piston engine reduces the emissions per fuel unit burned.  Research (SAE paper 2008-01-0928, website page Ingocar 2009) shows that the use of micro-hole nozzles (50 µm) reduces the emission of soot to an undetectable amount.  As an outcome, the primary compromise in exhaust gas composition (soot vs. nitrogen oxide) loses its importance and allows for a reduction of NOx.  When compared with the above research, the new peripheral micro-slot injection provides improved conditions regarding the size (20 µm width), number (16+) and location of nozzles (outer diameter of combustion chamber) and higher injection pressure (50,000 psi/3,500 bar) to allow for a significant reduction in NOx while keeping the soot nearly eliminated.