Cd (Coefficient of Drag)

(Gambar diatas adalah salah satu mobil yang sedang melakukan pengetesan Coefficient of Drag)

Cd atau Coefficient of Drag merupakan satuan dari nilai hambatan udara dari suatu benda yang bergerak. Kebanyakan satuan Cd dibuat untuk mengukur nilai hambatan udara kendaraan yang bergerak cepat seperti pesawat, mobil, dan motor. Para desainer kendaraan khususnya kendaraan sport harus memutar otaknya agar memperoleh nilai hambatan yang sekecil mungkin, hal ini dilakukan agar mesin kendaraan tidak perlu mengeluarkan tenaga lebih untuk membelah angin, maka hal itu akan membuat konsumsi BBM menjadi lebih irit. Untuk mobil F1 Cd yang bisa diperoleh sekitar 0,7 sampai 1,1 Cd. Semakin besar kendaraan, maka semakin besar pula nilai hambatan udara. Berikut adalah rumus untuk menghitung Coefficient of Drag sebuah kendaraan

Computer drawing of a rocket. Drag coefficient equals drag divided by the density times the area times half the velocity squared.

(http://exploration.grc.nasa.gov/education/rocket/dragco.html) <!–
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(http://en.wikipedia.org/wiki/Automobile_drag_coefficients)

Production cars
C_d	Automobile	Year
0.7 to 1.1	typical values for a Formula 1 car (downforce settings change for each circuit)
0.7	Caterham Seven
0.6 +	a typical truck
0.57	Hummer H2	2003
0.51	Citroën 2CV	1948
0.48	Volkswagen Beetle [6]
0.47	Lancia Aprilia	1937
0.46	Ford Mustang (coupe)	1979
0.45	Dodge Viper RT/10	1996
0.44	Ford Mustang (fastback)	1979
0.44	Peugeot 305	1978
0.44	Peugeot 504	1968
0.44	Toyota Truck	1990
0.425	Duple 425 coach (named for its low C_d by coach standards)	c.1985
0.42	Lamborghini Countach	1974
0.42	Triumph Spitfire Mk IV	1971
0.42	Plymouth Duster	1994
0.41	Volvo 740 (sedan)	1982
0.40	Ford Escape Hybrid	2005
0.40	Nissan Skyline GT-R R32	1989
0.39	Dodge Durango	2004
0.39	Triumph Spitfire	1964
0.38^[4] 0.39^[5]	VW NewBeetle without wing or spoiler	2003
0.385	Nissan 280ZX	1978
0.38	Mazda Miata	1989
0.374	Ford Capri Mk III	1978
0.372	Ferrari F50	1996
0.37	Renault Twingo
0.37	BMW Z3 M coupe	1999
0.37	Volkswagen Tiguan	2008
0.36	Citroën CX (named after the term for C_d)	1974
0.36	Citroën DS	1955
0.36	Chrysler Sebring	1996
0.36	Ferrari Testarossa	1986
0.36	Ford Mustang	1999
0.36	Honda Civic	2001
0.36	Opel GT	1969
0.355	NSU Ro 80	1967
0.35	Aston Martin Vanquish	2004
0.35	Dodge Viper GTS	1996
0.35	Jaguar XKR	2005
0.35	Toyota MR2	1998
0.35	BMW Z4 M coupe	2006
0.35	Volvo 940 (sedan)	1990
0.35	MINI Cooper	2008
0.34	Aston Martin DB9	2004
0.34	Chevrolet Caprice	1994
0.34	Ferrari F40	1987
0.34	Ferrari 360 Modena	1987
0.34	Ferrari F430 F1	1999
0.34	Ford Sierra	1982
0.34	Ford Puma	1997
0.34	Honda Prelude	1988
0.34	Mercedes-Benz SL (Roof Down)	2001
0.34	Peugeot 106	1991
0.338	Chevrolet Camaro, 1995
0.33	Audi A3	2006
0.33	Citroën SM	1970
0.33	Dodge Charger	2006
0.33	Ford Crown Victoria	1992
0.33	Honda Accord Sedan	2002
0.33	Lamborghini Murcielago	2001
0.33	Mazda RX-7 FC3C	1987
0.33	Peugeot 206	1998
0.33	Peugeot 309	1986
0.33	Renault Modus	2004
0.33	Subaru Impreza WRX STi	2004
0.324	Cobalt SS Supercharged	2005
0.32	AMC Pacer	1975-1980
0.32	Buick Riviera	1995
0.32	Dodge Avenger	1995
0.32	Honda Accord Coupe	2002
0.32	Mazdaspeed3	2007
0.32	McLaren F1	1992
0.32	Mercedes-Benz 190E 2.5-16/2.3-16
0.32	Nissan 300ZX	1989
0.32	Peugeot 406	1995
0.32	Peugeot 806	1994
0.32	Scion xB	2008
0.32	Suzuki Swift	1991
0.32	Toyota Celica	1994
0.32	Volkswagen GTI Mk V	2006
0.31	Audi A4 B5	1995
0.31	Citroën AX	1986
0.31	Citroën GS	1970
0.31	Eagle Vision	1995
0.31	Ford Falcon	1995
0.31	Holden Commodore	1998
0.31	Honda Civic (Sedan)	2006
0.310	Lamborghini Diablo	1990
0.31	Mazda RX-7 FC3S	1986
0.31	Mazda RX-7 FD R1(R2)	1993
0.31	Mazda RX-8	2004
0.31	Nissan Tiida / Versa	2004
0.31	Peugeot 307	2001
0.31	Renault 25	1984
0.31	Saab Sonett III	1970
0.31	Toyota Avalon	1995
0.31	Toyota RAV4	2006
0.31	Volkswagen GTI Mk IV	1997
0.30	Acura NSX	2005
0.30	Audi 100	1983
0.30	BMW E90	2006
0.30	Hyundai Sonata	2006
0.30	Honda Accord Sedan	2003, 2005-2007
0.30	Honda Odyssey	2005
0.30	Koenigsegg CCX	2006
0.30	Mitsubishi Eclipse	2000
0.30	Nissan 180SX	1989
0.30	Nissan 300ZX	1983
0.30	Nissan 350Z	2002
0.30	Porsche 996	1997
0.30	Porsche 997 GT3 RS	2007
0.30	Saab 92	1947
0.295	Ford Falcon	1998
0.291	Toyota Avalon	2005
0.29	Alfa Romeo 155	1992
0.29	BMW 8-Series	1989
0.29	Chevrolet Corvette	2005
0.29	Chevrolet Corvette C5 Z06	2002
0.29	Daewoo Espero	1990
0.29	Dodge Charger Daytona	1969
0.29	Eagle Talon	1990s [2]
0.29	Honda Accord Hybrid	2005, 2007
0.29	Honda Accord Coupe	2003, 2005-2007
0.29	Honda CRX HF	1988
0.29	Infiniti G35 Sedan	2008
0.29	Lancia Dedra	1990
0.29	Lexus LS 400	1990
0.29	Lotus Elite	1958
0.29	Lotus Europa	1966
0.29	Mazda Millenia	1995
0.29	Mazda RX-7 FC3S Aero Package	1986
0.29	Mazda RX-7 FD	1993
0.29	Mercedes-Benz SL (Roof Up)	2001
0.29	Mercedes-Benz W203 C-Class Coupe	2001
0.29	Nissan Versa	2007-2008
0.29	Peugeot 308	2007
0.29	Peugeot 407	2004
0.29	Peugeot 607	1999
0.29	Porsche Boxster	2005
0.29	Porsche 997 GT3	2006
0.29	Subaru XT	1985
0.29	Subaru SVX	1992
0.29	Toyota Prius	2001
0.28	Chevrolet Corvette Z06	2006
0.28	Citroën XM	1989
0.28	Citroën C4	2004
0.28	Lexus IS	2006
0.28	Mitsubishi Diamante	1995
0.28	Porsche 997	2004
0.28	Renault 25 TS	1984
0.28	Rumpler-Tropfenwagen	1921
0.28	Saab 9-3	2003
0.28	Toyota Camry / Lexus ES	2005
0.28	Volkswagen NewBeetle with wing	2003
0.27	Honda Civic Hybrid	2006
0.27	Infiniti G35 (0.26 with “aero package”)	2002
0.27	Hyundai Genesis	2009
0.27	Mazda6 (sedan and hatchback)	2008 ^[6]
0.27	Mercedes-Benz W203 C-Class Sedan	2001
0.27	Nissan GT-R	2008
0.27	Toyota Camry Hybrid	2007
0.27	Tucker Torpedo	1948
0.27	Volkswagen Passat B5 (sedan)	1997
0.27	Mercedes-Benz S Class (0.268 with Sport Package)	2000-2005
0.26	Hotchkiss Gregoire^{[citation needed]}	1951
0.26	Lexus LS 430 (0.25 with air suspension)	2001
0.26	Mercedes-Benz W221 S-Class	2006
0.26	Opel Calibra	1989
0.26	Toyota Prius	2004
0.25	Audi A2 1.2 TDI	2001
0.25	Honda Insight	1999, 2003, 2005
0.212	Tatra T77	1935
0.195	General Motors EV1	1996