What is average annual service cost for a 2000 E320?

I have owned 3 E320's over the past several years, a 1995, a 2000 rear wheel drive and a 2001 4-matic. All three had more than there fair share of issues and I have to say stacked up against Japanese cars they are far from the quality you would expect from an expensive German car. How much per year on average? About $2500

• $3000 per year.