Carwings in general is sluggish - and while I haven't messed with it yet, I think you can do it straight from Google Maps. Have you noticed the Google Maps 'Send to Car' feed in Carwings from the car's dash? (and the ability to make it a favorite/auto-update so it auto-updates when the car turns on?)
I've almost got it - but am missing one piece of info:
1. Go to http://maps.google.com/
2. enter in directions (like '123 elm st, 92069 to 123 main st, 92121) and click 'Search Maps' button to the right of the search box (very important - don't think send to car shows up without this)
3. Click on the 'send' link in the header bar (right side - envelope icon)
4. Choose 'Car' in the left side, name your directions, choose Nissan, enter your Carwings ACCOUNT#
(note - Carwings nickname doesn't appear to work)
5. Hit Send.
Only problem is - I can't find my Carwings Account # and a URL id I pulled when logged into Nissan's site isn't working. With that, I have a feeling this will be MUCH easier than route planner.
Anyone know where our Carwings Accout #s are?