They use the Romanian pronunciation. The name comes from the ancient kingdom of Dacia (now Romania)(http://en.wikipedia.org/wiki/Dacia).
Romanian is a Latin language so the letter group "ci" is pronounced like "chee" in English.
Written in English, to sound like the Romanian pronunciation, it will be: dha-chee-ah.
Belive me, I am Romanian. But you can read it the way you want, you are not Romanian. Even the french are pronouncing it in they're own way: dha-see-ah. So say it the way you want it. Day-cia sounds easier, and I think the majority will read it like this. It's a logical choice to read it with your own language pronunciation rules.
My apologies.........I trolled the chat thread for any previous not thinking that it would be dedicated to the Duster.It's been discused before here: http://www.daciaforum.co.uk/topic/276-dacia-pronunciation/
This was my answer: