Average Fuel Consumption at Increasing Road Grades
| -5% | -4% | -3% | -2% | -1% | 0% | 1% | 2% | 3% | 4% | 5% | |
| Midsize Sedan CV | 2.212322749812019 | 2.36766164522267 | 2.495770064622012 | 2.636553348642097 | 2.982695746841343 | 3.213049168323817 | 3.794709942123399 | 4.368556382225906 | 5.025996675413267 | 5.585506182994677 | 6.114217819808835 |
| Midsize Sedan HEV | 0.06471518799422755 | 0.1207160001492086 | 0.3871097988083085 | 0.852631071086249 | 1.477828516727381 | 1.982395144086719 | 2.459731696562222 | 3.064530212926774 | 3.664884515843766 | 4.231399756380166 | 4.901545916710673 |
| SUV CV | 3.065539608604173 | 3.273855523510499 | 3.420836190911564 | 3.589394941202374 | 4.033754789367468 | 4.324228778886487 | 5.127724528576058 | 5.91483125776826 | 6.82831985483853 | 7.612961459419679 | 8.318293132500528 |
| SUV HEV | 0.1473609150416523 | 0.2839799317354622 | 0.7415337357049412 | 1.401011103070829 | 2.27142620109198 | 2.995425496301589 | 3.654543601245803 | 4.495553904190317 | 5.301192512295914 | 6.067823170637369 | 7.027572988237496 |
| Midsize Sedan BEV | 0.06835185897300808 | 0.09554780711770813 | 0.1870588137526468 | 0.3370352002267759 | 0.5681504177346842 | 0.7592989231518441 | 0.9200317010408517 | 1.136251942986255 | 1.336960439408474 | 1.515825263612701 | 1.777452401046374 |
Source: National Renewable Energy Laboratory: Contribution of Road Grade to the Energy Use of Modern Automobiles Across Large Datasets of Real-World Drive Cycles, January 2014.
Notes: The majority of available data were for the 0% road grade. The amount of data tapers off with grade until it is not significant at 6% grade.
This chart shows how many gallons (in gasoline gallon equivalents [GGEs]) five different vehicle types consume over 100 miles as the road grade increases from -5% to 5%. As the hybrid electric vehicles (HEVs) and battery electric vehicles (BEVs) go downhill, their consumption drops to zero gallons per hundred miles as a result of their regenerative braking systems. In contrast, the conventional vehicles (CVs) still consume fuel at -5% grade. On an uphill grade, all cars consume more fuel than at a 0% grade. For HEVs and BEVs, fuel consumption increases steadily as road grade increases from -3% to 5%. On the other hand, conventional vehicle consumption increases steadily as the grade changes from downhill to flat, and then drastically increases on uphill grades. Both conventional and hybrid SUVs were more affected by incline than their sedan counterparts, most likely because they are heavier.
