A few things.

What do you mean by contacts transfer?

It is unfortunate that the N900 doesnt allow voice dialing, as it seems to be important to some users. It would also be natural to assume (though perhaps caution was needed?) that an N series device in 2009 would have this functionality, though MMS was also missing.

Anyway solutions. I am not aware of a 3rd party app, or a developer making one. Just look at how you can make the device work for you.

Dedicate a desktop screen to contacts you need to reach most often whilst driving, you can resize them and add many more if you need to. There is also portrait functionality available for the address back, so if your device is in a handsfree attached to the dashboard etc you can browse the address book easily.

Good luck.