Drastic cleanup and profile additions have been made.

Preface

While there a separate apps to locate your car, it can be done more efficiently and effectively with Tasker. Using this profile, there will be no need to remember to set your location. All you do is leave your car, and Tasker will remember do the rest.

This setup assumes that you have; (1) google nav installed on your phone, (2) a car dock or bluetooth, and (3) a GPS fix when you leave your car (no need to have google nav running).

Todo

-1- Make a profile with a car context that is triggered when you use your car (Car dock or bluetooth). [New > State > Docked/Car or Bluetooth Connected > Done.]

-2- For the Entering New Tasks: select
(1) + > Variable > Variable Clear > Name=%PARKPLATZ > Done, and
(2) + > Misc > GPS > On > Done, and
(3) Anything else you might want to use when in your car, such as enabling screen rotation.

-3- Select Done, then open the profile, click the enter task, and then select "Add Exit Task" from the popup.

-4- For the Exit New Tasks: select:
(1) + > Misc > Get Location > Source=GPS, Timeout=30secs > Done, then
(2) + > Variable > Variable Set > Name=%PARKPLATZ, To=%LOC > Done, and
(3) Whatever else you might have added earlier, you might want to have it turn off now.

-5- Select Done. On the main Tasker screen, select Apply.

-6- Make a new widget by long-pressing on a free space on your homescreen, choose Widget, then Task. You are now creating a widget icon, enter the following two Actions:
(1) + > Misc > GPS > On > Done, and
(2) + > App > Open Map > Mode=Point, Lat,Long=%PARKPLATZ > Done

-7- Click the icon, next to the tools, that looks like two multicolor stamp sheets ans select:
Application Icon > All (at the bottom of the popup) > Whatever icon looks good to you (I prefer Location).

-8- Click "Make Widget"

Have fun!

PS: You should test it, before you rely on it. :-)