Highway only? My roommate has one, I don't think he's ever not using autopilot even on side streets. He might only use the brake or accelerator a few times in a whole days driving.
> Traffic-Aware Cruise Control is primarily intended for driving on dry, straight roads,such as highways and freeways. It should not be used on city streets.
> Warning: Autosteer is intended for use only on highways and limited-access roads with a fully attentive driver. ... Do not use Autosteer on city streets, in construction zones, or in areas where bicyclists or pedestrians may be present.
Also this chip is SPECIFICALLY for FSD. Though true that current autopilot is not designed for city streets the "FSD Chip" / Telstra Computer is quite literally designed for slow city driving. And Elon specifically called out the power usage in these low speed scenarios.
Also even on the highway you're not using a lot of power in bumper-to-bumper traffic.
They also apparently had a power supply limitation in the older cars for retrofit.
> Warning: Autosteer is intended for use only on highways and limited-access roads with a fully attentive driver. ... Do not use Autosteer on city streets, in construction zones, or in areas where bicyclists or pedestrians may be present.
https://www.tesla.com/sites/default/files/model_s_owners_man...