Most specific engine output (power per unit volume)
Naturally-aspirated pistonless rotary engine - 140.5 kW
(191.1 PS/188.8 hp) /litre - Mazda RX-8 Renesis (184 kW (250 PS/247 hp) JIS 1.3 L)
Forced-induction pistonless rotary engine - 157.4 kW
(214.1 PS/212.3 hp)/litre - 2003 Mazda RX-7 13B-REW (206 kW (280 PS/276 hp JIS 1.3 L)
Petrol/Gasoline (naturally-aspirated) piston engine - 92.1 kW
(125.2 PS/123.7 hp)/litre - 2000 JDM Honda S2000 F20C (184 kW (250 PS/247 hp) JIS 2.0 L I4)
Honorable Mention: 91.9kW
(125PS/123.1hp)/Liter - Nissan Pulsar VZ-R SR16VE N1 (147 kW/200 PS/197hp 1.6L I4) (Limited production, about 1000 produced)
Honorable mention: 168 hp (125.3 kW)/litre - 2002 Radical Motorsport SR3 (252 hp (184 kW) 1.5 L I4 engine) - (Note: The Radical's status as a production car is disputed, and numbers refer to the competition version, there are no official data for the road version)
Honorable mention:
125 hp/liter - 1968 Alfa Romeo 33 Stradale (250 hp from a 2.0 liter V8 engine) - note: only 18 cars were built by the factory, at US$17,000 it was the most expensive car available to the public at the time.
Petrol/Gasoline (forced-induction) piston engine - 149 kW
(203 PS/200 hp)/litre 400 hp - 2005 Mitsubishi Lancer Evolution VIII FQ400 (298 kW (405 PS/400 hp) 2.0 L I4 (The FQ400's status as a "production car" is disputed)
Honorable Mention: 126 kW
(171.4 PS/169.7 hp)/litre (441 kW (600 PS/594 hp) DIN 3.5 L V12 quad-turbo) - Bugatti EB110 Super Sport
Honorable mention: 179.3 kW
(243.8 PS/240,5 kW)/litre (537 kW (730 PS/720 hp) 3.0 L flat-6 twin-turbo) - Dauer 962 LeMans (Road version of the Group C Porsche 962)
Diesel (naturally-aspirated) - 33.4 kW
(45.4 PS/44.7 hp)/litre (100 kW (136 PS/134 hp) DIN 3.0 L I6) - 1995 Mercedes E 300 D
Diesel (forced-induction) - 70.1 kW
(95.4 PS/94.1 hp)/litre (210 kW (286 PS/282 hp) DIN 3.0 L I6 twin-turbo) - 2006 BMW X3
Honorable Mention: 81.6 kW
(111 PS/109.5 hp)/litre (156 kW (212 PS/209 hp) 1.9 L I4 twin-turbo) - 2003 Opel Vectra OPC Concept (Not a production vehicle)