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Methods are provided for controlling a vehicle speed during a downhill travel. Based on the estimated grade of the downhill travel and further based on an input received from the operator, different combinations of an engine braking torque and a regenerative braking torque are used to maintain the v

Methods are provided for controlling a vehicle speed during a downhill travel. Based on the estimated grade of the downhill travel and further based on an input received from the operator, different combinations of an engine braking torque and a regenerative braking torque are used to maintain the vehicle speed during the downhill travel. A battery rate of charging is also adjusted based on the duration or distance of the downhill travel, as indicated by the operator input.

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1. A method for a vehicle including an engine and a battery-powered motor, comprising: adjusting a ratio and timing of applying engine braking torque relative to regenerative braking torque to the vehicle during a downhill travel based on an estimated grade and an operator input from an input device

1. A method for a vehicle including an engine and a battery-powered motor, comprising: adjusting a ratio and timing of applying engine braking torque relative to regenerative braking torque to the vehicle during a downhill travel based on an estimated grade and an operator input from an input device separate from an accelerator pedal and a brake pedal. 2. The method of claim 1, wherein the operator input is indicative of a request for downhill assistance, and wherein the input device separate from the accelerator pedal and the brake pedal is a button coupled to a dashboard of the vehicle. 3. The method of claim 1, wherein the operator input is indicative of a downhill grade being longer than a predetermined distance. 4. The method of claim 1, wherein the adjustment includes increasing a ratio of engine braking torque to regenerative braking torque applied to the vehicle during the downhill travel while applying the engine braking torque earlier in response to the operator input being received, and decreasing the ratio of engine braking torque to regenerative braking torque applied to the vehicle while applying the regenerative braking torque earlier in response to no operator input being received. 5. The method of claim 1, further comprising adjusting a rate of charging the battery based on the estimated grade and the operator input. 6. The method of claim 5, wherein the adjustment includes charging the battery at a lower rate in response to an operator input being received, and charging the battery at a higher rate in response to no operator input being received. 7. A method for a hybrid electric vehicle, comprising: during downhill travel,applying an engine braking torque, an amount and timing of the engine braking torque based on an estimated grade of the downhill travel and an operator input received via an input device separate from accelerator and brake pedals; andmaintaining a predetermined vehicle speed via applying a regenerative braking torque based on deviations from the predetermined vehicle speed during the downhill travel. 8. The method of claim 7, wherein the engine braking torque is not adjusted based on the deviations from the predetermined vehicle speed. 9. The method of claim 7, wherein the engine braking torque is maintained during the downhill travel while the regenerative braking torque is adjusted based on the deviations. 10. The method of claim 7, wherein the hybrid electric vehicle includes an engine, an electric motor, and a transmission coupled to the engine, and wherein a transmission gear is not shifted while maintaining the predetermined vehicle speed during the downhill travel, and further wherein the operator input is automatically cancelled in response to the estimated grade being less than a threshold or an increased engine torque request from an operator. 11. The method of claim 10, wherein the electric motor is powered via a battery, and further comprising adjusting a rate of charging of the battery based on the estimated grade and the operator input during the downhill travel. 12. The method of claim 11, wherein the operator input is indicative of a distance and/or duration of the downhill travel, and wherein the adjustment includes, as the distance and/or duration indicated by the operator input increases, decreasing the rate of charging of the battery. 13. A method for a vehicle including an engine and a battery, comprising: during a first downhill condition, applying engine braking torque at a first time since a first pedal foot-off event and charging the battery at a first rate; andduring a second downhill condition, applying engine torque at a second time since a second pedal foot-off event and charging the battery at a second rate, the second time later than the first time, the second rate higher than the first rate. 14. The method of claim 13, wherein a first duration of downhill travel during the first downhill condition is longer than a second duration of downhill travel during the second downhill condition, and wherein an estimated grade of downhill travel during the first downhill condition is same as the estimated grade of downhill travel during the second downhill condition. 15. The method of claim 13, wherein a first estimated grade of downhill travel during the first downhill condition is greater than a second estimated grade of downhill travel during the second downhill condition, and wherein a duration of downhill travel during the first downhill condition is same as the duration of downhill travel during the second downhill condition. 16. The method of claim 13, wherein during the first downhill condition, the vehicle is operated in a first downhill travel mode, and wherein during the second downhill condition, the vehicle is operated in a second downhill travel mode, the first downhill travel mode different from the second downhill travel mode. 17. The method of claim 16, wherein the first downhill condition is determined based on an operator input indicating a mountain-driving mode request. 18. The method of claim 13, wherein during the first condition, the downhill travel includes a first, higher change in barometric pressure since a preceding uphill travel, and wherein during the second condition, the downhill travel includes a second, lower change in barometric pressure since the preceding uphill travel. 19. The method of claim 13, wherein the engine is coupled to a transmission, and further comprising, during the first condition, maintaining a transmission gear; andduring the second condition, downshifting the transmission from a higher gear to a lower gear. 20. The method of claim 13, wherein during each of the first and second downhill conditions, a vehicle speed is maintained at a predetermined speed, the predetermined speed based on an estimated grade of a road and the position of one or more of a brake pedal and an accelerator pedal.