Let's start out by assuming you drive a Tesla and live in Westlake Hills.  You should have a trade-in Girlfriend at this point (can hire one).  As a matter of course, your regular activities should include cruising for the threesome in the UT or 6th Street area.  Offering cocaine works.

Ok, so your trade-in girlfriend is getting a little old, and you spot this absolutely gorgeous little number who breaks your heart.  You and your girlfriend run your pick-up routine and get the girl in the back seat of your Tesla.

While the Tesla is largely automated, you will have to install the auto-lock software to ensure the doors will not unlock without your smartphone.

As you are the good host, you can show your new girlfriend the auto-drive feature.  Leave your old girlfriend in the front seat, while you sit back with your new one.  You might offer her some cocaine at this point.

After pressing the auto-lock button on your smartphone, ensuring the doors cannot open, simply take something sharp and slice the neck open of your old girlfriend.  The Tesla should be on auto-home at this point.

A possible pick-up line for your new girlfriend might be, "I really liked my old girlfriend, until I met you."  Chat her up as normal, ask her where she is from, what her hobbies are and generally get to know her.  Be a gentleman.  (Psychologists might refer to this as "instant Stockholm Syndrome.)

Once you arrive at your home, park the car in the garage, take your new girlfriend inside and show her around.  Do not worry about your old girlfriend, we will take care of her tomorrow.  It is important for your new girlfriend to acclimate herself to her new surroundings and to feel comfortable.

The next morning, take your new girlfriend shopping and buy her everything she needs.  New clothes, perfume, maybe even get her a new hairdo.

After making love to her for the second or third time, you two should be feeling very comfortable with each other, so now it is time to handle the carcass of your old girlfriend.

You should have some land in Bastrop or some other location within an hour or two of Austin.  It should have a barn as well.  Program the auto-drive feature in the Tesla and have your new girlfriend take the driver's seat.  She might be a little uncomfortable with the carcass of your old girlfriend sitting next to her, but assure her that everything will be alright, program the destination, shut the door and press the auto-lock button.  Follow your girlfriend to your remote land and park the Tesla in the barn or garage.  Your new girlfriend will be so happy to get out of that vehicle and will very obediently get in the passenger seat as you drive her home.