Impact Of Vehicle Weight On Fuel Economy For Various .

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Impact of Vehicle Weight Reduction on Fuel Economyfor Various Vehicle ArchitecturesResearch ReportConducted by Ricardo Inc.for The Aluminum Association2008-04

Impact of Vehicle Weight Reduction on FuelEconomy for Various Vehicle ArchitecturesPrepared for: The Aluminum Association, Inc.By: Anrico Casadei and Richard BrodaProject FB769RD.07/71602.2Technical Approval: Reviewed by [Frederic Jacquelin]Date: Ricardo Inc 2007(20-Dec-2007)FB769 - RD.07/71602.2

Content Ricardo vehicle model development for high-level representation of existingvehicles Baseline vehicle selection Model inputs and assumptions Model validation Simulation Methodology Results– Gasoline vehicles– Diesel vehicles Ricardo Inc 2007 ConclusionsFB769 – RD.07/71602.2 2

Vehicle Modeling Using MSC.EASY5TM A full forward-looking, physics-based model was developed for each baselinevehicle using commercially available MSC.EASY5TM simulation software withRicardo proprietary data as well as published information. The model simulates what happens to the vehicle when the driver applies theaccelerator and/or brake pedal in order to achieve a certain vehicle speed ata certain time. The simulation runs on a millisecond-by-millisecond basis and predicts thefuel usage and actual speed with time as the model driver follows a certainvehicle speed trace (drive cycle). Ricardo Inc 2007 The model physics includes torques and inertias as well as detailed submodels for the influence of factors such as turbocharger lag and engineaccessories.FB769 – RD.07/71602.2 3

Example of Model Developed Using MSC.EASY5TM SoftwareFuel EconomyPost-processingToolsDriver ModelPowertrainModel Ricardo Inc 2007Vehicle ModelFB769 – RD.07/71602.2 4

Vehicle Model and Sub-Model Components Ricardo Inc 2007 Engine– Torque curves for full load and closed throttle motoring correlated topublished power ratings– Fuel consumption rates covering entire speed and load range– Idle and redline speeds– Rotational inertia– Turbo-lag model for turbocharged diesel engines– Alternator parasitic load (constant throughout drive cycle)– Power steering parasitic load as a function of engine speed– Cooling fan parasitic load Electric (Small Car, Mid-Size Car, Small SUV) fan loads specific to dutycycle Belt-driven (Large SUV, Truck) fan loads as a function of engine speedFB769 – RD.07/71602.2 5

Vehicle Model and Sub-Model Components Ricardo Inc 2007 Transmission– Torque converter characteristic curves for torque ratio and capacity factor– Gear ratios– Shift and lock-up clutch strategy maps for all engine throttle positions andvehicle speeds– Efficiency and pumping losses for each gear– Rotational inertiasFB769 – RD.07/71602.2 6

Vehicle Model and Sub-Model Components Final drive differential– Gear ratio– Efficiency– Rotational inertia Ricardo Inc 2007 The spin losses of the 4-wheel drive vehicle’s front axle were also included inthe model to simulate the fuel economy and performance of the 4-wheel drivepowertrain operating in 2-wheel drive mode (similar to EPA procedure foremissions and fuel economy certification testing).FB769 – RD.07/71602.2 7

Vehicle Model and Sub-Model Components Vehicle– Configuration (FWD, RWD or AWD)– Weight (front / rear distribution)– Center of gravity– Wheelbase– Frontal area– Coefficient of drag (Cd) Ricardo Inc 2007 Wheels / Tires– Rolling resistance coefficients– Rotational inertia– Rolling radius (tire size)– Maximum friction coefficient– Slip at peak tire force Driver– Drive cycle (time vs. velocity trace)FB769 – RD.07/71602.2 8

Vehicle Selection Five vehicle classes were chosen to represent a variety of vehicle weights andengine sizes in the U.S passenger and light-duty truck vehicle fleet. A specific comparator vehicle for each class was chosen to verify that eachvehicle model was representative of the class. Ricardo Inc 2007 Vehicle Class / Comparator Vehicle:– Small Car / Mini Cooper– Mid-Size Car / Ford Fusion– Small SUV / Saturn Vue– Large SUV / Ford Explorer– Truck / Toyota TundraFB769 – RD.07/71602.2 9

Ricardo Inc 2007Model Input – Vehicle ParametersFB769 – RD.07/71602.2 10

Ricardo Inc 2007Model Input – Baseline Gasoline Engine and TransmissionFB769 – RD.07/71602.2 11

Diesel Engine Selection Diesel engines were selected to provide improved fuel economy andacceptable (not equivalent) vehicle performance. Ricardo Inc 2007 The characteristic turbocharged diesel power curve (high torque at low speed)has more torque in the typical cruising and light acceleration engine operatingrange (1100 – 3000 RPM). At 50 to 70 MPH in 6th gear the diesel providesmore reserve torque so that light pedal “tip-in” acceleration demands aresuperior to the gasoline engine. Full pedal (WOT) accelerations at thesespeeds will be slower due to the lower maximum engine speed of the diesel(4000 RPM) and resultant lower horsepower vs. the high speed gasolineengine (5600 – 6500 RPM).FB769 – RD.07/71602.2 12

Diesel Engine Power Curve 2.7L V6 Diesel vs. 3.6L V6 Gasoline Engines3502.7L Diesel Torque3003.6L Gas HPEngine Torque / HP2503.6L Gas Torque2002.7L Diesel HP15010050 Ricardo Inc 2007001000200030004000500060007000Engine RPMFB769 – RD.07/71602.2 13

Ricardo Inc 2007Model Input – Baseline Diesel Engine and TransmissionFB769 – RD.07/71602.2 14

Model Input – Downsized Gasoline Engines Ricardo Inc 2007(Displacement reduced to provide equivalent performance to baseline vehicles)FB769 – RD.07/71602.2 15

Model Input – Downsized Diesel Engines Ricardo Inc 2007(Displacement reduced to provide equivalent performance to baseline vehicles)FB769 – RD.07/71602.2 16

Model Validation Each vehicle model was run and the simulation output for total vehicle roadloadtractive effort from 0 to 60 MPH and EPA City and Highway fuel economy wascompared to published data for the comparator vehicle. No attempt was made to “calibrate” the model to achieve a given output result.SimulationRoadload Force Ricardo Inc 2007VEHICLESimulated Fuel Economy vs. Comparator (% diff)MaximumVariation vs.ComparatorEPA CityEPA HighwayCombinedSmall Car0.2%2.5%-0.6%1.3%Mid-Size Car2.5%0.2%-1.4%-0.4%Small SUV1.1%1.8%-4.4%-0.4%Large SUV1.7%5.9%-1.1%3.5%Truck-1.3%2.2%-1.9%0.7%FB769 – RD.07/71602.2 17

Vehicle Simulations Vehicle fuel economy (MPG) is simulated over the following drive cycles at EPAEquivalent Test Weight (ETW):– EPA FTP75 (city)– EPA HWFET (highway)– ECE (European)– Steady State 30, 45, 60 and 75 MPH All simulations are performed with an engine at normal operating temperature.The EPA FTP (city) cycle result is obtained by using a bag #1 correction factorof 0.8 (bag #1 fuel economy 80% of bag #3 fuel economy) Ricardo Inc 2007 Vehicle acceleration performance (sec.) is simulated over the following drivecycles at loaded vehicle weight conditions (GCVW for truck):– 0 – 10 MPH– 0 – 60 MPH– 30 – 50 MPH– 50 – 70 MPH Each vehicle is weight reduced by 5%, 10% and 20% and the enginedownsized to match the baseline vehicle acceleration performance. Fueleconomy benefits are recorded.FB769 – RD.07/71602.2 18

Simulation Drive Cycles60EPA HighwayVehicle Velocity (MPH)5040Euro ECEEPA City302010 Ricardo Inc 20070020040060080010001200140016001800Time (sec)FB769 – RD.07/71602.2 19

Vehicle Performance Matching The Wide Open Throttle (WOT) performance of each vehicle is simulated at aloaded weight condition to approximate what a customer would expect from agiven class of vehicle (number of passengers, luggage or trailer towing). Allfuel economy simulations are performed at ETW. Additional Performance Weight:– Small Car – 300 lb. (2 passengers)– Mid-Size Car – 450 lb. (3 passengers)– Small SUV – 550 lb. (3 passengers 100 lb. Luggage)– Large SUV – 750 lb. (5 passengers)– Truck – 9800 lb. (Trailer load to rated combined weight of 15,800 lb.) Ricardo Inc 2007 Engines were downsized in displacement to give the weight reduced vehiclesequivalent performance to the baseline vehicle with a priority given to passingmaneuvers (30-50 and 50-70 MPH).FB769 – RD.07/71602.2 20

Fuel Economy Labeling of Vehicles The EPA requires that all new light-duty motor vehicles have a fuel economy label thatgives the consumer an estimate of the city and highway fuel economy. This estimate isused to compare to the fuel economy of other vehicles that they may be considering forpurchase. Prior to the 2008 model year, the City fuel economy prediction for the vehicle windowsticker was calculated as 90% of the EPA Federal Test Procedure (FTP) result and theHighway fuel economy was 78% of the EPA Highway Fuel Economy Test (HWFET)result. Starting with the 2008 model year, new test methods that include high speeds,aggressive accelerations, cold temperatures and the use of air conditioning have beenintroduced to more accurately reflect real world fuel economy. Ricardo Inc 2007 As a transition to the increased testing requirements, a manufacturer has the option ofusing a “derived 5-cycle” approach for fuel economy labels for the 2008-2010 modelyears that uses only the FTP and HWFET tests based on regression formulae derivedfrom the fuel economy test results of more than 600 vehicles in the EPA database(subject to revision as more data becomes available).– City MPG 1 / (0.003259 (1.1805 / FTP MPG))– Highway MPG 1 / (0.001376 (1.3466 / HWFET MPG))FB769 – RD.07/71602.2 21

Results Ricardo Inc 2007 Vehicles with Gasoline EnginesFB769 – RD.07/71602.2 22

Small Car – 1.6L-4V gas engine with variable intake and exhaust camtiming and lift Ricardo Inc 2007 Fuel Economy Simulation ResultsEPA fuel economy label projections are based on the derived 5-cycle regression equation for the 2008 model year.FB769 – RD.07/71602.2 23

Small Car – 1.6L-4V gas engine with variable intake and exhaust camtiming and lift Ricardo Inc 2007 Vehicle Performance Simulation Results at Wide Open Throttle (WOT)FB769 – RD.07/71602.2 24

Mid-Size Car – 3.0L-4V gas engine with variable intake cam timing Ricardo Inc 2007 Fuel Economy Simulation ResultsEPA fuel economy label projections are based on the derived 5-cycle regression equation for the 2008 model year.FB769 – RD.07/71602.2 25

Mid-Size Car – 3.0L-4V gas engine with variable intake cam timing Ricardo Inc 2007 Vehicle Performance Simulation Results at Wide Open Throttle (WOT)FB769 – RD.07/71602.2 26

Ricardo Inc 2007Mid-Size Car – Additional Engine Downsizing Study Fuel economy simulation results with gasoline engine downsized to vehicle performance level at ETW(Degraded vehicle acceleration performance vs. baseline at loaded weight) Engine displacement is further reduced by 0.1% per 1% of weight reduction with a resultantimprovement in fuel economy of 0.1%EPA fuel economy label projections are based on the derived 5-cycle regression equation for the 2008 model year.FB769 – RD.07/71602.2 27

Mid-Size Car – Additional Engine Downsizing Study Ricardo Inc 2007 Vehicle performance simulation results with gasoline engine downsized to vehicle performance levelat ETW (Degraded vehicle acceleration performance vs. baseline at loaded weight)FB769 – RD.07/71602.2 28

Small SUV – 3.6L-4V gas engine with variable intake cam timing Ricardo Inc 2007 Fuel Economy Simulation ResultsEPA fuel economy label projections are based on the derived 5-cycle regression equation for the 2008 model year.FB769 – RD.07/71602.2 29

Small SUV – 3.6L-4V gas engine with variable intake cam timing Ricardo Inc 2007 Vehicle Performance Simulation Results at Wide Open Throttle (WOT)FB769 – RD.07/71602.2 30

Large SUV – 4.6L-3V gas engine Ricardo Inc 2007 Fuel Economy Simulation ResultsEPA fuel economy label projections are based on the derived 5-cycle regression equation for the 2008 model year.FB769 – RD.07/71602.2 31

Large SUV – 4.6L-3V gas engine Ricardo Inc 2007 Vehicle Performance Simulation Results at Wide Open Throttle (WOT)FB769 – RD.07/71602.2 32

Truck – 5.7L-4V gas engine with variable intake and exhaust camtiming Ricardo Inc 2007 Fuel Economy Simulation ResultsEPA fuel economy label projections are based on the derived 5-cycle regression equation for the 2008 model year.FB769 – RD.07/71602.2 33

Truck – 5.7L-4V gas engine with variable intake and exhaust camtiming Ricardo Inc 2007 Vehicle Performance Simulation Results at Wide Open Throttle (WOT)FB769 – RD.07/71602.2 34

Ricardo Inc 2007Fuel Economy Improvement (%) per 100 lb. Weight Reduction Gasoline EnginesFB769 – RD.07/71602.2 35

Drive Cycle Fuel Economy Improvement (%) per 100 lb. Weight Reduction Gasoline EnginesEngine Downsizedto Baseline PerformanceBaseline Engine3.03.02.52.5FuelEconom y 2.0Increaseper 100 lb. 1.5WeightReduction1.0(%)Sm all CarMid-Size CarSm all SUV0.5Sm all CarMid-Size CarSm all SUV0.5Large SUVLarge ined Ricardo Inc 20070.0FuelEconom y 2.0Increaseper 100 lb. 1.5WeightReduction1.0(%)FB769 – RD.07/71602.2 36

Steady State Fuel Economy Improvement (%) per 100 lb. Weight Reduction Gasoline EnginesEngine Downsizedto Baseline PerformanceBaseline Engine2.52.52.0Sm all SUV0.5Large SUVTruck75 MPH60 MPH45 MPH30 MPH Ricardo Inc 20070.0Mid-Size CarSm all SUV0.5Large SUVTruck0.075 MPHMid-Size CarSm all Car60 MPHSm all Car45 MPHFuelEconom yIncrease 1.5per 100 lb.Weight1.0Reduction(%)FuelEconom yIncrease 1.5per 100 lb.Weight1.0Reduction(%)30 MPH2.0FB769 – RD.07/71602.2 37

EPA City (FTP75) Drive Cycle – Fuel Economy Improvement (%) Gasoline EnginesEngine Downsizedto Baseline Performance Ricardo Inc 2007TruckLarge SUVSmall SUVR e d u c t io n( %)20%10%We ig h t5%Mid-Size CarTruckLarge SUVSmall SUVMid-Size CarSmall Car20%10%We ig h t5%181614Fuel12Econom y 10Increase 86(%)420Small Car181614Fuel12Econom y 10Increase 86(%)420Baseline EngineR e d u c t io n( %)FB769 – RD.07/71602.2 38

EPA Highway (HWFET) Drive Cycle – Fuel Economy Improvement (%) Gasoline EnginesEngine Downsizedto Baseline Performance Ricardo Inc 2007TruckLarge SUVSmall SUVR e d u c t io n( %)20%10%5% We ig h tMid-Size CarTruckLarge SUVSmall SUVMid-Size CarSmall Car20%10%We ig h t5%181614Fuel12Econom y 10Increase 86(%)420Small Car181614Fuel12Econom y 10Increase 86(%)420Baseline EngineR e d u c t io n( %)FB769 – RD.07/71602.2 39

EPA Combined Drive Cycle – Fuel Economy Improvement (%) Gasoline EnginesEngine Downsizedto Baseline Performance Ricardo Inc 2007TruckLarge SUVSmall SUVR e d u c t io n( %)20%10%5% We ig h tMid-Size CarTruckLarge SUVSmall SUVMid-Size CarSmall Car20%10%We ig h t5%181614Fuel12Econom y 10Increase 86(%)420Small Car181614Fuel12Econom y 10Increase 86(%)420Baseline EngineR e d u c t io n( %)FB769 – RD.07/71602.2 40

European (ECE) Drive Cycle – Fuel Economy Improvement (%) Gasoline EnginesEngine Downsizedto Baseline Performance Ricardo Inc 2007TruckLarge SUVSmall SUVR e d u c t io n( %)20%10%5% We ig h tMid-Size CarTruckLarge SUVSmall SUVMid-Size CarSmall Car20%10%We ig h t5%201816Fuel14Econom y 12Increase 108(%)6420Small Car201816Fuel14Econom y 12Increase 108(%)6420Baseline EngineR e d u c t io n( %)FB769 – RD.07/71602.2 41

Results Ricardo Inc 2007 Vehicles with Diesel EnginesFB769 – RD.07/71602.2 42

Mid-Size Car – 2.2L I4 diesel engine Ricardo Inc 2007 Fuel Economy Simulation ResultsEPA fuel economy label projections are based on the derived 5-cycle regression equation for the 2008 model year.FB769 – RD.07/71602.2 43

Mid-Size Car – 2.2L I4 diesel engine Ricardo Inc 2007 Vehicle Performance Simulation Results at Full Engine Load (WOT)FB769 – RD.07/71602.2 44

Small SUV – 2.7L V6 diesel engine Ricardo Inc 2007 Fuel Economy Simulation ResultsEPA fuel economy label projections are based on the derived 5-cycle regression equation for the 2008 model year.FB769 – RD.07/71602.2 45

Small SUV – 2.7L V6 diesel engine Ricardo Inc 2007 Vehicle Performance Simulation Results at Full Engine Load (WOT)FB769 – RD.07/71602.2 46

Large SUV – 3.2L V6 diesel engine Ricardo Inc 2007 Fuel Economy Simulation ResultsEPA fuel economy label projections are based on the derived 5-cycle regression equation for the 2008 model year.FB769 – RD.07/71602.2 47

Large SUV – 3.2L V6 diesel engine Ricardo Inc 2007 Vehicle Performance Simulation Results at Full Engine Load (WOT)FB769 – RD.07/71602.2 48

Truck – 4.8L V8 diesel engine Ricardo Inc 2007 Fuel Economy Simulation ResultsEPA fuel economy label projections are based on the derived 5-cycle regression equation for the 2008 model year.FB769 – RD.07/71602.2 49

Truck – 4.8L V8 diesel engine Ricardo Inc 2007 Vehicle Performance Simulation Results at Full Engine Load (WOT)FB769 – RD.07/71602.2 50

Ricardo Inc 2007Fuel Economy Improvement (%) per 100 lb. Weight Reduction Diesel EnginesFB769 – RD.07/71602.2 51

Drive Cycle Fuel Economy Improvement (%) per 100 lb. Weight Reduction Diesel EnginesEngine Downsizedto Baseline PerformanceBaseline Engine3.03.02.52.5FuelEconom y 2.0Increaseper 100 lb. 1.5WeightReduction1.0(%)Mid-Size CarSm all SUV0.5Mid-Size CarSm all SUV0.5Large SUVLarge ined Ricardo Inc 20070.0FuelEconom y 2.0Increaseper 100 lb. 1.5WeightReduction1.0(%)FB769 – RD.07/71602.2 52

Steady State Fuel Economy Improvement (%) per 100 lb. Weight Reduction Diesel EnginesEngine Downsizedto Baseline PerformanceBaseline Engine2.52.52.00.5Large SUVTruck75 MPH60 MPH45 MPH30 MPH Ricardo Inc 20070.0Sm all SUV0.5Large SUVTruck0.075 MPHSm all SUVMid-Size Car60 MPHMid-Size Car45 MPHFuelEconom yIncrease 1.5per 100 lb.Weight1.0Reduction(%)FuelEconom yIncrease 1.5per 100 lb.Weight1.0Reduction(%)30 MPH2.0FB769 – RD.07/71602.2 53

EPA City (FTP75) Drive Cycle – Fuel Economy Improvement (%) Diesel EnginesEngine Downsizedto Baseline Performance Ricardo Inc 2007We ig h tR e d u c t io n( %)5%TruckTruckLarge SUVSmall SUVMid-Size Car5%10%Large SUV10%20%Small SUV20%181614Fuel12Econom y 10Increase 86(%)420Mid-Size Car181614Fuel12Econom y 10Increase 86(%)420Baseline EngineWe ig h tR e d u c t io n( %)FB769 – RD.07/71602.2 54

EPA Highway (HWFET) Drive Cycle – Fuel Economy Improvement (%) Diesel EnginesEngine Downsizedto Baseline Performance Ricardo Inc 2007We ig h tR e d u c t io n( %)5%TruckTruckLarge SUVSmall SUVMid-Size Car5%10%Large SUV10%20%Small SUV20%181614Fuel12Econom y 10Increase 86(%)420Mid-Size Car181614Fuel12Econom y 10Increase 86(%)420Baseline EngineWe ig h tR e d u c t io n( %)FB769 – RD.07/71602.2 55

EPA Combined Drive Cycle – Fuel Economy Improvement (%) Diesel EnginesEngine Downsizedto Baseline Performance Ricardo Inc 2007We ig h tR e d u c t io n( %)5%TruckTruckLarge SUVSmall SUVMid-Size Car5%10%Large SUV10%20%Small SUV20%181614Fuel12Econom y 10Increase 86(%)420Mid-Size Car181614Fuel12Econom y 10Increase 86(%)420Baseline EngineWe ig h tR e d u c t io n( %)FB769 – RD.07/71602.2 56

European (ECE) Drive Cycle – Fuel Economy Improvement (%) Diesel EnginesEngine Downsizedto Baseline Performance Ricardo Inc 2007We ig h tR e d u c t io n( %)5%TruckTruckLarge SUVSmall SUVMid-Size Car5%10%Large SUV10%20%Small SUV20%201816Fuel14Econom y 12Increase 108(%)6420Mid-Size Car201816Fuel14Econom y 12Increase 108(%)6420Baseline EngineWe ig h tR e d u c t io n( %)FB769 – RD.07/71602.2 57

Summary – EPA Combined Drive Cycle % Improvement in Fuel Economy per % Weight Reduction The fuel economy benefit from weight reduction is similar for gasoline and diesel powered light dutyvehicles. Truck engines were downsized to a lesser degree than the passenger vehicle engines due to theperformance demands on trucks when loaded. Vehicles rated to tow a trailer benefit the least fromweight reduction and subsequent engine downsizing if acceleration performance while towing ismaintained.% Improvement in Fuel Economy / % Weight ReductionEPA Combined (Metro-Highway) Drive Cycle Ricardo Inc 2007Passenger VehicleT

Five vehicle classes were chosen to represent a variety of vehicle weights and engine sizes in the U.S passenger and light-duty truck vehicle fleet. A specific comparator vehicle for each class was chosen to verify that each vehicle model was representative of the class. Vehicle Class / Compa

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