1. Instantaneous Power Requirements of A Vehicle
P M V Subbarao
Professor
Mechanical Engineering Department
Match the Horse to the Car….

2. Comprehensive Test Driving Cycle for Design of Horse for A Vehicles

3. Driving on Busy Roads : Braking & Safety
In general, if we're talking normal driving situations the rule of thumb you should follow is to keep the car in gear for the most amount of time.
Downshifting is good, but most people do not downshift when stopping.
This can either just be laziness!!!
It is also driven by the fact that when you need to slow down reasonably fast you might just not have enough time to row through the gears. 
Best way to do is, brake in gear until the car about the slowest speed for whatever gear it is in, then clutch in, go into neutral and keep braking further.

4. Forces To be Overcome by an Automobile

5. Resistance Forces on A Vehicle
The major components of the resisting forces to motion are comprised of :
Acceleration forces (Faccel = ma & I forces)
Aerodynamic loads (Faero)
Gradeability requirements (Fgrade)
Chassis losses (Froll resist ).

6. Aerodynamic Force : Flow Past A Bluff Body
Composed of:
Turbulent air flow around vehicle body (85%)
Friction of air over vehicle body (12%)
Vehicle component resistance, from radiators and air vents (3%)

7. Aerodynamics Lift, Drag and Down Force

8. Aerodynamic Drag on Vehicle
Dynamic Pressure:
Drag Force:
Aero Power

9. Instantaneous Power Requirement to Overcome Drag
Cd = coefficient of drag  = air density  1.2 kg/m3
A = projected frontal area (m2)
V = vehicle velocity (m/sec)
Vw = head wind velocity

10. Purpose  Shape  Design Drag

11. Shape & Components of Drag

12. Some examples of Cd:
The typical modern automobile achieves a drag coefficient of between 0.30 and 0.35.
SUVs, with their flatter shapes, typically achieve a Cd of 0.35–0.45.
Notably, certain cars can achieve figures of , although sometimes designers deliberately increase drag in order to reduce lift.
at least a typical truck
Hummer H2, 2003
Citroën 2CV
over Dodge Viper
Toyota Truck,

13. Drag Coefficient for Sports Cars
General Motors EV1, 1996
Alfa Romeo BAT Concept, 1953
Dodge Intrepid ESX Concept , 1995
Mercedes-Benz "Bionic Car" Concept, 2005 ([2] mercedes_bionic.htm) (based on the boxfish)
Daihatsu UFEIII Concept, 2005
General Motors Precept Concept, 2000
Fiat Turbina Concept, 1954
Ford Probe V prototype, 1985

14. Transient Nature of Aerodynamic Drag

15. Effect of Overtaking on Aerodynamic forces : Overtaking Vehicle is behind the main Vehicle

16. Effect of Overtaking on Aerodynamic forces : Overtaking & Main Vehicles at same Position

17. Effect of Overtaking on Aerodynamic forces : Overtaking Vehicle is ahead of the Main Vehicle

18. Effect of relative velocity on the variation in the aerodynamic Drag coefficient

19. Force System on A Rolling Wheel

20. Road Conditions & Rolling Resistance

21. Rolling Resistance Composed primarily of
Resistance from tire deformation (90%)
Tire penetration and surface compression ( 4%)
Tire slippage and air circulation around wheel ( 6%)
Wide range of factors affect total rolling resistance
The magnitude of this force is Approximated as:
Rolling resistance of a vehicle is proportional to the component of weight normal to the surface of travel

22. Typical Values of Coefficient of Rolling Resistance
Contact Type
Crr
Steel wheel on rail
Car tire on road
Car tire energy safe
Tube 22mm, 8 bar
0.002
Race tyre 23 mm, 7 bar
0.003
Touring 32 mm, 5 bar
0.005
Tyre with leak protection 37 mm, 5 bar / 3 bar
0.007 / 0.01

23. Effect of Road Condition on Crr

24. Grade Resistance Composed of Gravitational force acting on the vehicle
For small angles, θg Fg θg mg

25. Total Vehicular Resistance at Constant Velocity
  AR = air resistance [N]
RR = rolling resistance [N]
            GR = gradient resistance [N]
TR = total resistance [N]