Hi Frank,
That doesn’t sound right. I was a Hyundai Salesman for 5 years until 2010 (just when they introduced the 2nd version of the mk 2. I had a few 2.2 crdi autos as demos and I was averaging 32mpg, but that was purely town driving. I was rarely on the motorways.
I know they up’d the power on the latest model (I think around 160 ish BHP) and I’m sure they introduced a Diesel Particulate Filter.
Depending on who you purchased the car from (private sale or dealer), I would take it to a Hyundai Main Dealer and ask them to check it out. Their warranty is fantastic, so if there is an issue, you shouldn’t have any problem getting it fixed, just remember to stick to the servicing intervals and keep your book stamped.
Good luck.