In-car satnav and GPS tracking for OSM - choice of devices?

I’m gettin an in-car satnav shortly, i.e. in the next week. I would like to get one that can also do GPS tracking for OSM. I’m quite good with computers, but know little about GPS.
I’m inclined towards a Garmin Nuvi 760 or similar, for other reasons. I’d also go for a TomTom 700 series. I can’t now afford this and another €130 for a separate tracking GPS.
Can either of these record GPS tracks in a way relevant to OSM, and if so, how?
If not, are there any other purpose-designed car satnav units that can?
Anthony Staines

I don’t know about Garmin Satnav, but there are quite a few OSM mapping apps that work on TomTom:

Just did a Wiki search and found this for Garmin Nuvi: