I drive my new ICE car to work very early in the morning. Then, I open a fenced-gate before parking my car at work. I have to exit the car to get the gate open. I choose to shut off the engine during those few seconds while 25 feet away from my vehicle. Finally, I re-start the car and park the car only about 500 feet away. This happens five days each week.
Will this engine shut-off and immediate re-start cause harm to turbo-charged engines if repeated for years?
No, you’ll be fine. But if the place you park is close to the place you tap the card, be sure to drive gently for the last mile or so unless you have a turbo timer. The main trouble with shutting off an engine on a hot turbo is that the turbo stays hot for a long time, and the oil that’s in the very hot turbo doesn’t circulate out of it, and ends up cooking. A 50 foot jaunt back and forth isn’t going to give the oil enough time to cook, but if you then park it immediately and leave it for hours, that would.
25 feet is less than 2 car lengths. You’re worried about someone lurking around and stealing the car? Aren’t you also/more worried about being robbed?
I don’t see any mechanical issues to worry about, but you could always leave the car running, lock the door and use a spare key to unlock it 20 seconds later.
I am certain this mystery car has a warranty. My cars are for my use to do what I want, not the other way around. Unless you drove to work kicking in the Turbo every chance you got there is nothing to worry about.
Nothing to worry about.
Volvo has, by the way, offered an excellent point. 
Play an MP3 of a barking German Shepherd when you’re outside the car. No one will want to jump in it then.
car has a warranty
If stopping and re-starting causes damage which builds slowly over time, the vehicle may not show it until well after all extended-warranties have expired.
HondaGuy-Do you just lay awake at night trying to think of things to worry about?
HondaGuy70 has a very valid point.
I wouldn’t even consider turning off and restarting any car as you describe, but that’s just me. I think turning things on-off-on-off is just a generally bad idea.
Here’s an idea: have a second key made and lock the door with it when you step away to unlock the gate. It’s always good to have a spare key in your pocket anyway.
I have to assume that other people use this gate also. Why don’t you watch what they do and do the same thing. They have figured this one out. If you insist on stopping and restarting, let the engine idle for at least 30 seconds before shutting it off, this will give the oil some time to circulate through the turbo and cool off.
What’s wrong with letting it idle for a minute? The amount of fuel burned is negligible and with the constant shutting off and restarting you’re just adding more key cycles and wear to the switch, relays, and starter motor.
Apparently the OP’s work place is in a neighborhood with a higher car theft rate than most. Having to unlock a gate to get in the parking lot suggests that.
I used to regularly visit a company on business that was in a really bad section of Roxbury, and they had 8-foot chain link fencing with barbed wire on top around their parking lot. The first time I visited there I drove in, and they admonished me never to do that again. They had me park in a parking lot outside the area and came to pick me up when I visited. The company owner told me they had their employees park in a “park & ride” lot outside of the area and picked them all up in a company van, dropping them off again at the day’s end. He also told me that they made sure they were all out of the area before the sun set every day.
I still think carrying a spare key and locking the car door when stepping away (leaving the engine running) is the best solution in this case.
Back in the day, when I had working air conditioner and a dog, I did lots of traveling with the dog. When I had to leave her in the car and go inside a gas station, restaurant, or rest area, I would leave the car running with the air conditioner on, lock the Club (or similar theft deterrent) onto the steering wheel, and then use a spare valet key to lock the doors. Maybe the OP should consider doing something similar, locking the doors and immobilizing the car in case someone considers smashing the window.
I don’t see the issue. If you need to cool the turbo down prior to shutoff, it makes no difference if you do that before approaching the gate or if you were to go directly to your parking spot and have to idle there for a period of time. It has to be done before shutoff regardless of where that shutoff occurs. Once cooled, it makes no significant difference if you start it back up for a short jaunt to the final spot (unless you plan to kick in the turbo in that 500ft trek 
Can’t you just drive more gently in the last few miles to your work and eliminate the worry?
True, but restarting it every time does double the wear on the starter.
I’m all for the taped German Shepherd Bark. At that distance any potential thief will think twice before coming even near the car!