Abstract
Today, the full hybrid system as opposed to the advanced diesel engine with particulate filter is in the focus of discussion as the powertrain solution for fuel savings and exhaust emissions reduction. The discussion about the best concept for the near future and the cost-benefit equation can be regarded as controversial.
This paper reviews the capabilities of the following powertrain concepts: the gasoline full hybrid, the advanced diesel engine and the diesel full hybrid, to consider the advantages and disadvantages of the three systems with regard to fuel consumption and exhaust emissions. The Lexus RX 400 h gasoline full hybrid vehicle currently available on the market was used as basis for this comparison. This vehicle was investigated in a study carried out in the framework of the hybrid activities of the Department of Internal Combustion Engines at the University of Technology Darmstadt.
The advantages of the diesel engine of today as a fuel-efficient powertrain providing excellent driveability are undisputed, making the diesel engine very popular in Europe. Due to significant advances in combustion and exhaust aftertreatment the diesel passenger car is accessing new markets, even in the USA. The major negative aspect of diesel engines are the high NOx emissions compared to a gasoline engine with regulated TWC.
Similar fuel economies as with the diesel can be reached with gasoline full hybrids which have significantly lower NOx emissions but are more costly compared to a diesel vehicle.
Due to the inherent advantages of the Diesel engine and the lower fuel price, the diesel full hybrid should offer the best opportunities for the European market. But the diesel engine itself is significantly more expensive than a gasoline engine and shows a range of technical problems that can complicate the realisation of a diesel hybrid.
Keywords:Hybrid, powertrain, advanced diesel, fuel consumption, emissions.