# EP

A/Alliance/Global 4WD Dyno Correlation Factor Program Preliminary Data Review

6 - 13 - 13

# Overview: 4WD - to - 2WD Correlation Factor Te st Program **Goal:** Eva luate need / quantify 4WD d yno c orr elation f act or . Such a f act or wo uld be used adjus t FE & CO2 fo r an y tests perf ormed using 4WD dynamometer to ensure that an y “g ener al” 2WD vs. 4WD dyno testing bias is not inappr opriately attributed to the specific v ehicle types tha t ar e targeted f or 4WD dyno testing.
• 12 ve hicles, 10 labs • 3 r oad load deriv at ions in each mode (a ve ra ge used f or FE testing) • 4 FE tests in each mode (FTP , Hwy , US06).

# Alliance Preliminary Analysis
• Analysis still underwa y; pr esen te d data is pr eliminary • Err or checking not complete


# • Incomplete BMW Data Set was not included • No individual B1, B2, B3 Dat a (FTP) • No individual US06 City or US06 Highw ay D ata • Missing /e rroneous drive dat a 

# • Re commend that EP

A Impala data set be r e - exa mined • Intr a - lab 2WD - to - 4WD correlation significantly diff er ent (vs. EP A Explor er) • Impala shows diver gent highwa y r esult vs. Explor er and over all dat aset

# Road Load Derivations

# 2WD vs. 4WD Dyno Coef ficients

170 160 150 140 130 120 110 100 90 80 140 120 100 80 60 40 **TR L50**  **Me an** **R L** **5 0** **M e** **a n**  

## 2W D 4W D Dy noSt at

Wr an gl er Wr an gl er

OU TBACK OU TBACK

Im pa la Im pa la G25 G25 Fit Fit Ex plor er Ex plor er

Es ca pe Es ca pe CX -5 CX -5

ACCO RD ACCO RD 4Runner 4Runner 

# Sc **at te**  **rp lo**  **t of**

**R L50**  **Me an**  **v s**  **TR L50**  **Me an** 

4WD 2WD 90 80 70 60 50 40 30 20 10 0**M e** **a n** **o f** **R L** **5 0** **_ M** **e a** **n** 

### 59.0032

79.2927

Work sh eet: Copy

of Work sh eet 1 

### Ch **ar t of**  **Me an**  **( RL50_M**  **ean )**  **l bs** 


#  **2WD dyno ABC ’s**  **~ 25% higher**

# RL Curve Comparison

• Po in t - to - point comparison (i.e. RL Fo rc e @50) • “P owe r Integr al” (PI) • Integr al of power - vs - speed curv e fr om 10 – 70 mph • Pr oportional to the r oad - load ener gy re quir ed t o driv e a cons tant acceler at ion tr ace fr om 10 - 70 mph. • Ea sily calculated fr om polynomial coefficients:



#   70 10 2 2 1 3 3 1 4 4 1 70 10 2 3 

# AV BV CV dV AV BV CV PI       

# 

# 4W D 2W D 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 4W D 2W D 1. 8 1. 6 1. 4 1. 2 1. 0 0. 8 0. 6 0. 4 0. 2 0. 0 RL 50_C Variat ion 1**M e** **a n**  

# PI _CV ari at ion2 1. 64346

0. 676318 1. 61894

0. 688451 

# Ro **ad L**  **oa d C**  **oe ffi**  **ci en**  **t of**  **V ar**  **ia ti**  **on %**  **( R**  **L50, Po**  **we r**  **In te**  **gr al**  **)**

Co mpa res " ABC" cu rv

es @ 50mph point Co mpa re s " ABC" cu rv e pow er ov

er 10- 70mph 

# 2WD vs. 4WD RLD V

ariability

 **Overall, 4WD RLD variability > 2x 2WD** 

# 4W D 2W D 4000 3000 2000 1000 0**P I** **_ S** **t D** **e v** **2** Wrangler
OUT BACK Im pala

G2 5 Fi t
Ex plorer Es ca pe

CX -5 ACCO RD 4R unne r

Wrangler

OU TBACK Im pa la G2 5

Fit Ex plor er

Es ca pe

CX -5 ACCO RD 4R unner 

# 2174.2 **1348. 77**  

# Ro **ad L**  **oa d P**  **owe r**  **In te**  **gr al**  **S tan**  **da rd**  **De vi**  **at io**  **n** 

# 2WD vs. 4WD RLD V

ariability

# 4W D 2W D 4 3 2 1 0**P I** **_ C** **V a** **r i** **a t** **i o** **n 2** 

Wrangler OUT BACK Im pala

G2 5 Fit

Ex plorer Es ca pe

CX -5 ACCO RD 4R unne r

Wr angler OU TBACK Imp al a G25
Fi t Ex plor er

Es ca pe CX -5 ACCO RD 4R unner 

# 1. **61894 0.688451**  

# Ro **ad L**  **oa d P**  **owe r**  **In te**  **gr al**  **- C oe**  **ffi ci**  **en t of**  **V ar**  **ia ti**  **on (**  **%)** 

# 2WD vs. 4WD RLD V

ariability

# FE Results

## US0 6H US0 6C US0 6 Hw y C i ty _C om p B3 B2 B1 3. 00% 2. 00% 1. 00% 0. 00% -1. 00% -2. 00% -3. 00% -4. 00% -5. 00%**F E** **_ p** **e r** **_ 4** **- 2**  To yo ta

SU BARU NI SSA N Mi ts ubis hi Ma zd a

Ho nda F Ho nda A

Fo rd EPA I
EPA E

Ch ry sl er To yo ta

SU BARU

NI SSA N Mi ts ubis hi Ma zd a

Ho nda F Ho nda A Ford EPA I

EPA E Ch rys ler To yo ta

SU BARU NISSA N Mi ts ubis hi Ma zd a

Hon da F Hon da A

Ford EPA I
EPA E

Ch rys ler BMW

To yo ta SU BARU

NI SSA N Mi ts ubis hi Ma zd a Hon da F Hon da A Fo rd EPA I

EPA E

Ch ry sl er BMW
To yota SU BARU NI SSA N Mi ts ubis hi Ma zd a
Ho nda F Ho nda A Ford EPA I EPA E Ch rys ler BMW To yo ta SU BARU NISSA N

Mi ts ubis hi Ma zd a

Hon da F Hon da A Ford EPA I EPA E
Ch rys ler To yota SU BAR U NI SSA N

Mi ts ubis hi Ma zd a Ho nda F Ho nda A Ford EPA I EPA E Ch rys le r To yota SU BAR U
NI SSA N Mi ts ubis hi Ma zd a
Ho nda F Ho nda A Ford EPA I EPA E Ch rys le r**- 1** **. 0** **9 %** **- 1** **. 3** **9 %** **- 0** **. 9** **6 %** **- 0** **. 6** **7 %** **- 1** **. 0** **7 %** **- 0** **. 8** **0 %** **- 0** **. 9** **5 %** **- 1** **. 8** **5 %**  

# 95% CI for the Me an 

# FE **De lt**  **a (4**  **WD-2 WD)**  **% - Al**  **l Da**  **ta**

## US0 6H US0 6C US0 6 Hw y C i ty _C om p B3 B2 B1 3. 00% 2. 00% 1. 00% 0. 00% -1. 00% -2. 00% -3. 00% -4. 00% -5. 00%**F E** **_ p** **e r** **_ 4** **- 2** **- 1** **. 0** **9 %** **- 1** **. 3** **9 %** **- 1** **. 2** **4 %** **- 0** **. 7** **5 %** **- 1** **. 1** **6 %** **- 0** **. 8** **0 %** **- 0** **. 9** **5 %** **- 1** **. 8** **5 %**  To yo ta

SU BARU NI SSA N Mi ts ubis hi Ma zd a

Ho nda F Ho nda A

Fo rd EPA I
EPA E

Ch ry sl er To yo ta

SU BARU

NI SSA N Mi ts ubis hi Ma zd a

Ho nda F Ho nda A Ford EPA I

EPA E Ch rys ler To yo ta

SU BARU NISSA N Mi ts ubis hi Ma zd a

Hon da F Hon da A

Ford EPA I
EPA E

Ch rys ler To yo ta SU BARU

NI SSA N Mi ts ubis hi Ma zd a Hon da F Hon da A Fo rd EPA I

EPA E

Ch ry sl er To yota SU BARU NI SSA N Mi ts ubis hi Ma zd a
Ho nda F Ho nda A Ford EPA I EPA E Ch rys ler To yo ta SU BARU NISSA N

Mi ts ubis hi Ma zd a

Hon da F Hon da A Ford EPA I EPA E
Ch rys ler To yota SU BAR U NI SSA N

Mi ts ubis hi Ma zd a Ho nda F Ho nda A Ford EPA I EPA E Ch rys le r To yota SU BAR U
NI SSA N Mi ts ubis hi Ma zd a
Ho nda F Ho nda A Ford EPA I EPA E Ch rys le r 

# 95% CI for the Me an 

# FE **De lt**  **a (4**  **WD-2 WD)**  **% - C**  **om pl**  **et e**  **Da ta**  **S et**  **s** (No BMW Dat a)

# Impala Results

Concern:  Dir ectionally opposite highw ay re sult fr om ov er all da taset  Lar ge diff er ence in 4WD - to - 2WD correlation: (1) within same lab (same site, r es tr aints, per sonnel?), (2) between “passiv e” 2WD ve hicles 4W D 2WD 28.50 28.25 28.00 27.75 27.50 **Dy no**  **M ode (2W**  **D or**  **4W D)** **F E** **_ b** **a g** **( m** **p g** **)**
27. 7675 27.7345 

## Indi **vid ua**  **l Val**  **ue P**  **lo t**  **of F**  **E_ ba**  **g ( mp**  **g)** La b = EPA E

4WD 2WD 37.0 36.5 36.0 35.5 35.0 34.5 **Dy no**  **M ode (2**  **WD or 4**  **WD )** **F E** **_ b** **a g** **( m** **p g** **)** 36. 2177

35. 2105 

## Indi **vid ua**  **l Val**  **ue P**  **lo t**  **of F**  **E_ ba**  **g ( mp**  **g)** La b = EPA I 

# FE Of fset (4 - 2) = 0.12% FE Of fset (4 - 2) = **2.78%**

## US0 6H US0 6C US0 6 Hw y C i ty _C om p B3 B2 B1 3. 00% 2. 00% 1. 00% 0. 00% -1. 00% -2. 00% -3. 00% -4. 00% -5. 00%**F E** **_ p** **e r** **_ 4** **- 2** **- 1** **. 3** **4 %** **- 1** **. 6** **1 %** **- 1** **. 4** **7 %** **- 1** **. 1** **0 %** **- 1** **. 2** **5 %** **- 0** **. 9** **7 %** **- 1** **. 0** **0 %** **- 1** **. 9** **5 %**  To yo ta

SU BARU NI SSA N Mi ts ubis hi Ma zd a

Ho nda F Ho nda A

Fo rd EPA E

Ch ry sl er To yo ta

SU BARU

NI SSA N Mi ts ubis hi Ma zd a

Ho nda F Ho nda A Ford EPA E Ch rys ler To yo ta

SU BARU NISSA N Mi ts ubis hi Ma zd a

Hon da F Hon da A

Ford EPA E

Ch rys ler To yo ta SU BARU

NI SSA N Mi ts ubis hi Ma zd a Hon da F Hon da A Fo rd EPA E

Ch ry sl er To yota SU BARU NI SSA N Mi ts ubis hi Ma zd a
Ho nda F Ho nda A Ford EPA E Ch rys ler To yo ta SU BARU NISSA N

Mi ts ubis hi Ma zd a

Hon da F Hon da A Ford EPA E
Ch rys ler To yota SU BAR U NI SSA N

Mi ts ubis hi Ma zd a Ho nda F Ho nda A Ford EPA E Ch rys le r To yota SU BAR U
NI SSA N Mi ts ubis hi Ma zd a
Ho nda F Ho nda A Ford EPA E Ch rys le r 

# 95% CI for the Me an 

# FE **De lt**  **a (4**  **WD-2 WD)**  **% - R**  **eco mme**  **nd ed**  **Da ta**  **S et**  (No BMW , No Impala)

# Regression Modeling

• Need t o account f or driv e - st yle impacts • Demons tr ate significance of dyno - mode • Model FE = ƒ (V ehicle, EER - j2951, Dyno Mode 

# )

# Regression Modeling - Example

**Regression An**  **aly sis:**  **FE_bag (mpg) versus EER (j2951),**  **Dy no**  **Mode_4WD, ...** * Lab_Toyota is highly correlated with other X variables * Lab_Toyota has been removed from the equation. The regression equation is FE_bag (mpg) = 29.6 - 0.347 EER (j2951) - 0.372 Dyno Mode_4WD

- 6.33 Lab_Chrysler - 1.75 Lab_EPA E + 8.80 Lab_Ford + 21.2 Lab_Honda A + 19.5 Lab_Honda F + 15.9 Lab_Mazda + 7.59 Lab_Mitsubishi + 11.6 Lab_NISSAN + 11.6 Lab_SUBARU 78 cases used, 1 cases contain missing values Predictor Coef SE Coef T P Constant 29.5651 0.1236 239.28 0.000 EER (j2951) - 0.3474 0.1411 - 2.46 0.016 Dyno Mode_4WD - 0.37184 0.07608 - 4.89 0.000 Lab_Chrysler - 6.3344 0.1665 - 38.04 0.000 Lab_EPA E - 1.7509 0.1736 - 10.08 0.000 Lab_Ford 8.8009 0.1780 49.45 0.000 Lab_Honda A 21.2309 0.1785 118.96 0.000 Lab_Honda F 19.4684 0.1711 113.76 0.000 Lab_Mazda 15.9353 0.1664 95.74 0.000 Lab_Mitsubishi 7.5904 0.1807 42.01 0.000 Lab_NISSAN 11.6232 0.1702 68.30 0.000 Lab_SUBARU 11.5888 0.1678 69.08 0.000 S = 0.332523 R - Sq = 99.9% R - Sq(adj) = 99.9%

# Modeling Results

Model Fit (R^2) 4WD Coef 4WD Coef Significance 

# Drive

Coef Drive Coef Significance 

# FE (4 - 2 )



# (Model/Drive Corrected) 

# FE (4 - 2) 

# ( AV G) **FTP** 

# 99.9% **- 0.3174**  **100.0% -**  **0.1374 90.1%**  **- 1.2%**  **- 1.3%**  **Hwy** 

# 99.9% **- 0.3718**  **100.0% -**  **0.3474 98.4%**  **- 1.0%**  **- 1.1%**  **US06C** 

# 99.0% **- 0.2901**  **100.0% -**  **0.1229 76.1%**  **- 1.8%**  **- 1.6%**  **US06H** 

# 99.7% **- 0.3137**  **99.9% -**  **0.3133 94.7%**  **- 1.1%**  **- 1.3%**  

#  **4WD Dyno mode is**  **a significant factor**   **4WD Dyno mode reduces FE in all models/phases (high**  **correlation variation**  **across vehicles)**   **Correcting for drive style**  **(i.e., regression model) has minimal impact on**  **resulting 4WD**  **- to**  **- 2WD FE offset (see model FE delta vs. data set average)** 

# Summary • Note: Analysis is pr eliminary . • Ave ra ge r oad load v ariability higher on 4WD dyno’ s • Quantification of impact TBD 

# • Dyno mode is significant f act or • 4WD corr elation fa ctor is needed • Drive r ating also a significant FE f actor but did not bias dyno f actor 

# • Va riation in 4WD - to - 2WD corr ela tion using simple 2WD ve hicles is a concern • Magnitude of corr elation diff er ences suggests that f actor s other than vehicles diff er ences ( i.e., diff er ences in the “passive” non - drive axle of the te st vehicles) ar e r esponsible. • Additional study/best pr actices ar e needed! 4WD dyno contr ol s ystems (load split ting), re str aints/tie - down/ sk ew , br ak e dr ag , et c. ar e all possible contributor s. • Bottom Line: If 4WD dyno correlation is not predict able/well unders to od for simple, “passive” 2WD vehicles, we cannot assume that a lower FE result on a 4WD dyno t es t is attribut able solely t o AW D /HEV “a ctive” attribut es ( AW D sy ste m, regen braking).