Can you do that with a nuvi? My wife has one in her company car and while I have not pushed every button, I have played with the nuvi a good bit and have not seen where I could get the unit to display raw position lat/lon. There is a screen to input a lat/lon you wish to navigate to, and the unit will draw a nice magenta line to the destination but I haven't found how to make our Nuvi show me the lat/lon of my current position.Well, it can probably be used to some degree, since it should be able to give you your lat/lon position. Then you can plot that on the chart.
Just as commentary, I started using GPS in airplanes long before they became common for use in cars. As the aviation handheld units evolved over the years, they had automotive capability added as a "nice to have" feature, but retained all the aviation funtionality, which made them very useful in my opinion. I feel like the latest evolution of car units are incredibly "dumbed down" from even earliest aviation units with automotive features. The 3d view doesn't provide the same situational awareness to help YOU decide when a detour might be a good idea and the mapping display sux compared to older units. It seems now the units are tailored and marketed to people that want to blindly follow the magenta line and eventually get there, not folks that want to see where they are, the suggested route and be able to evalutate possible alternatives.