A fun-to-drive, economical and environmentally-friendly mobility solution

  • Alberto A. Boretti RMIT University


Kinetic energy recovery systems (KERS) placed on the rear non-motored axle of a small, lightweight, forward drive passenger car with a turbocharged direct injection (TDI) internal combustion engine (ICE) is possibly the best solution presently available to dramatically improve the fuel economy of today’s passenger cars within today’s constraints of budget, weight, packaging, simple construction, easy operation and best life cycle environmental friendliness. The vehicle may be built by using different KERS designs, from the purely mechanical M-KERS based on a continuously variable transmission and a flywheel permitting round trip regenerative braking efficiencies above 80% but requesting additional research and development, to purely electric E-KERS systems based on an electric motor/generator and a battery with off the shelf components permitting round trip regenerative braking efficiencies above 70% but having however the traction battery as the weak part of the design, to mixed mechanical-electric systems EM-KERS adopting an electromechanical flywheel replacing the traction battery for intermediate advantages and downfalls. The engine is small displacement, small number of cylinders, high power density, turbocharged, direct injection. The TDI ICE may be gasoline or diesel, with higher power density but lower fuel conversion efficiency or vice-versa, with or without start-stop capability, to deliver high part load efficiencies over the reduced off idle operating points of a driving cycle. Downsizing, down speeding and KERS assistance permits to reduce the operation of the thermal engine over non-efficient BMEP x speed map points in addition to the thermal engine energy supply reduction by regenerative braking. The front wheel drive vehicle behaves as a four wheel drive during the driving characterized by accelerations and decelerations, with the thermal engine torque boosted by the KERS.The proposed vehicles may have fuel economy figures well below 2.5 litres/100 km covering a modified NEDC where the unrealistic sharp deceleration from 120 km/h to rest at the end of the extra urban sector is followed by another urban sector as the first four ones.


1. International Energy Agency (2012), Monthly Electricity Statistics. July 2012. www.iea.org/stats/surveys/MES.XLS
2. MAN (2013), Marine applications.
3. MAN (2013), Power.
4. Boretti, A. (2013), Kinetic Energy Recovery Systems for Racing Cars. SAE International, Warrendale, PA, USA. ISBN: 978-0-7680-7994-4. books.sae.org/book-pt-159/
5. Boretti A (2012), A Novel Mechanical Kinetic Energy Recovery System to Improve the Performances and Reduce the Fuel Consumption and the Pollutant Emissions, FISITA EUROBRAKE 2012 Conference, 16-18 April 2012, Dresden, Germany. www.fisita.com/publications/papers?id=7660
6. Boretti A. and Scalzo J (2012), Novel Crankshaft Mechanism and Regenerative Braking System to Improve the Fuel Economy of Passenger Cars, Lecture Notes in Electrical Engineering Volume 189, 2013, pp 19-44.
doi: 10.1007/978-3-642-33841-0_2.
7. Audi media services (2012), R18 e-tron.
8. Williams Hybrid Power (2013), The technology. www.williamshybridpower.com/technology/the_flywheel/#%2Ftechnology
9. Boretti, A., (2010), Coupling of a KERS Power Train and a Downsized 1.2TDI Diesel or a 1.6TDI-JI H2 Engine for Improved Fuel Economies in a Compact Car, SAE Technical Paper 2010-01-2228. doi:10.4271/2010-01-2228.
10. Boretti, A. (2010), Analysis of Design of Pure Ethanol Engines, SAE Technical Paper 2010-01-1453. doi:10.4271/2010-01-1453.
11. Boretti, A. (2010), Use of Variable Valve Actuation to Control the Load in a Direct Injection, Turbocharged, Spark-Ignition Engine, SAE Technical Paper 2010-01-2225. doi:10.4271/2010-01-2225.
12. Boretti, A. (2010), Performances of a Turbocharged E100 Engine with Direct Injection and Variable Valve Actuation, SAE Technical Paper 2010-01-2154. doi:10.4271/2010-01-2154.
How to Cite
BORETTI, Alberto A.. A fun-to-drive, economical and environmentally-friendly mobility solution. Journal of Power Technologies, [S.l.], v. 93, n. 4, p. 194--201, dec. 2013. ISSN 2083-4195. Available at: <https://papers.itc.pw.edu.pl/index.php/JPT/article/view/459>. Date accessed: 14 july 2024.


vehicles, powertrains, internal combustion engines, kinetic energy recovery systems

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