More than likely it's the A/C (if equipped). I can recall the same in a couple of Fords I've driven in the past -- a Crown-Vic and an E-350 Van. Not sure exactly what part of the air-con it was -- the refrigerant lines or condenser.
Ok. It wasn't on, but I do have the option. It must be the way the pipes are routed.
It's a shame I can't show you the engine. I will open the hood again this weekend. If I can figure out how not to break it, I will remove the covers.
We had a 2006 Sc?nic in the fall of 2005 on our European tour. It too was the 1.9 dCi engine, with 130 HP and 300 Nm of torque (225 lbs*ft). The car was great, would top 200 km/h (124 MPH) with ease - peak was about 127 MPH (see photo). We drove it on Autobahnen, Autoroutes, Autostrade etc and in heavy city traffic in Paris, Rome and other places. The overall average fuel consumption with five aboard plus luggage for a month was 6.6 L/100 km (36 US MPG), with absolutely ZERO attention being paid to economical driving.
I wish I could have one of them here. The Mercedes B-Class is the closest thing to it in Canada, but it's only available with the gasser engine here.