I think Lutz is wrong or mistaken with those weights. I have just traded my C5 2.0 HDI LS Estate in and the max tow for that was 1500 Kgs. The 2.2 was the same. Kerb weights for the 2.0 and the 2.2 where 1439 and 1501 ish giving an 85% tow of 1222 and 1275 ish. The 2.0 110 bhp towed my Bailey Ranger 1259 MTPLM very well at approx 32 mpg towing and a very good 45mpg here and there ing. The 2.2 is similar with a slightly better perfomance towing from its 130 bhp HDI engine. There are 90 bhp models, avoid those for towing unless you have a very light van.The newer model C5 have a different spec and the 2.0 ltr model is now the better for towing with its uprated engine at 130 bhp, you will have to check its towing limits though. Comfort and room is excellent but residual prices for trade in are poor. There where some problems with early moddles, mainly electrical, do a search for C5 Problems and check over any likely candidates carefully before you buy one. Not so much a problem if it still has waranty. On the whole, I found mine very good and only changed it because of the poor residual prices and the waranty had expired.
Good Luck Brian