Lane change advisor

1. A method, comprising:

while piloting a vehicle by adaptive cruise control:

determining a lane change maneuver based on the adaptive cruise control and determined traffic in an adjacent lane; and

displaying a prompt to an occupant based on the lane change maneuver, including displaying a safe field of travel based on an available lateral acceleration, wherein the available lateral acceleration is a function of a coefficient of friction and a longitudinal acceleration, and the safe field of travel is further based on factors including an intended lane change distance and a lane change maneuver time.

2. The method of claim 1 , wherein piloting a vehicle by adaptive cruise control includes controlling the vehicle to maintain a target speed.

3. The method of claim 2 , wherein controlling the vehicle to maintain the target speed does not include braking to a stop.

4. The method of claim 1 , further comprising determining the traffic in the adjacent lane including by determining position, speed, and direction of one or more other vehicles.

5. The method of claim 1 , wherein determining the lane change maneuver includes determining a merge into traffic in the adjacent lane.

6. The method of claim 1 , wherein displaying the prompt includes delivering a haptic output via a steering wheel.

7. The method of claim 6 , wherein a force and a frequency of the haptic output is based on the lane change maneuver.

8. The method of claim 1 , wherein displaying the prompt includes displaying a visual prompt including turn signal blinking.

9. The method of claim 8 , wherein a frequency and a direction of the visual prompt is based on the lane change maneuver.

10. The method of claim 1 , wherein displaying the prompt includes sounding an audio alert.

11. A computer apparatus, comprising a processor and a memory, the memory storing instructions executable by the processor, such that the computer is programmed to:

pilot a vehicle by adaptive cruise control;

determine a lane change maneuver based on the adaptive cruise control and determined traffic in an adjacent lane; and

display a prompt to an occupant based on the lane change maneuver, including displaying a safe field of travel based on an available lateral acceleration, wherein the available lateral acceleration is a function of a coefficient of friction and a longitudinal acceleration, and the safe field of travel is further based on factors including an intended lane change distance and a lane change maneuver time.

12. The apparatus of claim 11 , the computer further programmed to pilot the vehicle by adaptive cruise control including controlling the vehicle to maintain a target speed.

13. The apparatus of claim 12 , the computer further programmed to control the vehicle to maintain the target speed without braking to a stop.

14. The apparatus of claim 13 , the computer further programmed to determine traffic in the adjacent lane including by determining position, speed, and direction of one or more other vehicles.

15. The apparatus of claim 11 , the computer further programmed to determine the lane change maneuver by determining a merge into traffic in the adjacent lane.

16. The apparatus of claim 11 , the computer further programmed to display the prompt by delivering a haptic output via a steering wheel.

17. The apparatus of claim 16 , wherein a force and a frequency of the haptic output is based on the lane change maneuver.

18. The apparatus of claim 17 , the computer further programmed to display the prompt by displaying a visual prompt including turn signal blinking.

19. The apparatus of claim 18 , wherein a frequency and a direction of the visual prompt is based on the lane change maneuver.

20. The apparatus of claim 11 , the computer further programmed to display the prompt by sounding an audio alert.