Not sure it will work in the specific position you mentioned, but Thoughtfix has tried the N810's GPS when mounted with the car-mounting kit, and it does work.

a) Transflective screen will help in-car usage too.
b) You really don't want to be leaving a bluetooth device in the car. For that matter, a GPS mount is an inviting sign for thieves. Something they can see on a BT scanner tells them there's something valuable and portable inside.
c) Hey, using an external BT GPS + N810 sounds cool, but you have range issues. If you use two n810s (or n800s with BT GPS) and an ad hoc connection, you'd get more range, wouldn't you?

Sure would be. But it's getting very costly.

As for storing you location when you park your car, yes that'd work and it'd be nice to have a simple app that stores a location then later gives you a direction and distance to it.

But people never plan to lose their cars and are going to get bored of manually storing the location every time they park. You need something that is a no-brainer. I think there's a new Garmin unit (Nuvi 700?) that provides just this service - it automatically stores the location when you remove it from the car mount.

Can the range of bluetooth be extended using this method?

If you only can find me a maemo coder I can provide you with the same feature at Nokia tablet for free.

Darius

Differential GPS in both senses is precisely the same thing; the only difference is how the results are represented. In either case, the GPS reading is taken at two places at practically the same time. The difference is computed. In the "normal" case, the result is then added to the precisely known location of one point. For the situation with both endpoints unknown, the only data that can be given is the difference.

In both cases, however, the measurements must be taken together. The drift in the signal will cause a progressive loss in accuracy the longer you are in the store, so you might only find your car to the same level of accuracy you can get in general, after a few hours. Still, at least for car-finding, that's probably close enough.
And presumably, if you have some BT gadget you leave in the car (maybe a handsfree), you can recognise the disconnect when you walk away, and automatically save a position there. A daemon to do this would be nice, and I'd probably write one if I had an N810. (anyone want to buy me one? please? I was afraid of that :-)

Yeah, another thing about BT GPS Transceivers: they auto shutoff after 5 minutes. But, well, that'd be good enough too, right. When the BT signal on the GPS transceiver goes out, log the position.

Other problems with finding cars are that they're often parked in garages.

Many cars are getting BT installed for various things. If you're going to write the BT disconnect demon, may I suggest the following options as well:

a) record the position on a significant and unreversed degradation of the signal (rssi or lq?) as when someone gets out of a car.
b) events for when a known BT MAC comes into range. This would be very useful when wired to the MAC of the Boss's cellphone. Make a desktop widget too and call it "KittyBell". It woudl probably help you find your car too.

This could be interesting:

http://artico.lma.fi.upm.es/numerico...nio/pd/pd.html

is for etrex gps, but could it be usefull?
It uses RINEX files to compare and do diferential postprocess gps