Still quite liking the Synergie - honest. It's a bus in comparison to the golf GTI, but I worked in the building trade for years. Driving a van suits me :-))
HDi is much more linear than the VAG TDI. Power starts building from around 1,500rpm, becomes useful at 1,750 and is really strong around 2,000 onwards. Don't know what it does after 3,000 as I've never gone there - I usually change up at 2,500rpm. :-)
It's quite unlike the VAG engine which seems to do SFA until 1,900 rpm then wham, where did all that come from.
Fuel wise. Been running on biodiesel for around a month now. There's a place near me who sells it for a rather splendid 85p per litre. I go about 60/40 bio/dino. Starts fine even in the cold we were getting a little while back there. May mover over to 100% once it warms up a bit further.
Also considering a plug in tuning module. Another 20bhp and about 35lb/ft of torque would be most welcome.