I've had my 20v since 2001, been all over the place in it. I took it down through Austria to Slovenia a few years ago, thats about 850 miles each way, never missed a beat. I drove across Germany from Metz in France to Salzburg in Austria in one day without a problem.
Keep it serviced and check the fluid levels regularly and you'll be fine. I've never heard of a Marea with a failed HG.