If you are moving your residence to Greece then you may be eligible for a CERTIFICATE FOR DOMICILE TRANSFER EXEMPTION. If that is the case then you are pretty much exempt from import tariffs on your personal possessions. That is what thebigbluecheese is referring to. Full details here
. You will probably need to employ some sort of import agent to deal with the process at this end but the cost should be in the low hundreds of Euro including transfer of car registration.
If you do not qualify for the exemption then there is no import duty on the vehicle but there is a fee to transfer to a Greek registration. That is not a fixed fee but a percentage that varies with a lot of factors. The UK value of the car or what you paid for it is totally irrelevant. A Greek customs officer will look up what the vehicle would have cost in Greece when it was brought into circulation. If it was not sold in Greece he will make an estimate based on nearest models. My best guess would be around €55,000. If you look at today's models the price would be somewhere around €75,000. That is based on current models E200 about €62,000, E350 about €79,000, E220d about €68,000 and E350d about €83,000. Inflation from 2004 up to today would be somewhere around 37 % so divide €75,000 by 1.37 to get a 2004 price. He would then depreciate that price according to the age of the car. For a 16 year old car the depreciation would be 80% of the value so the effective price today would be around €11,000. Since the car is above 2,001 cc the fee is 88% of that effective price so around €9,500. That is an estimate so don't rely on it, consult an import agent. They shouldn't charge you much to tell you what it will cost.
You can bring the car for up to 6 months without transferring the registration so another option is to use it to drive down and get settled and then drive back to the UK and sell it there. That is what I did. If you intend to transfer the registration start the process immediately, do not wait 6 months and then try.
If you transfer it by paying the full fee then I think it will be on normal plates so in theory you could sell it at any time, assuming you can find someone who wants to buy a right hand drive car. If you transfer it through the exemption certificate then I think it will be on red plates and you cannot sell it for 5 years. There are many cars on red plates not just imports. Some Greek families qualify for a tax reduction on a new car and they are also on red plates and subject to the sale restriction.
I think that model is just under 3,000 cc? If so the annual circulation tax, equivalent to UK road tax, would be €840 per year. If it is above 3,000 cc then that rises to €1,050. If you become tax resident you would also be subject to a luxury tax each year but I don't know the amount. I always stick to cars less than 1,929 cc which are not subject to the luxury tax.
PS Cars first registered after 31/10.2010 have a circualtion tax based on emissions not engine size.