I have had my 2.7 Auto Santa Fe for 5 months and love it! definitely the
best value SUV...one problem persists however, a whining noise in the
cabin (I think from the transmission) when in top gear cruising at 40mph
or motorway speeds, and when decelerating. I have found examples of this
happening on the net in the US but not in the UK. My dealer hasn't a clue
what to do....does anyone have experience of such an issue?

 

Any issues of this I've seen have been noise transmittance issues, not any
issue with the transmission itself. I did have one with a very loud
transfer case whine, but it was very apparently a real problem and easily
identifiable by any reasonable tech, so I don't think that's what you're
talking about.

In the U.S., we have a tsb about a final drive whine noise for 01-03 Santa
Fes which instructs us to install a damper on the shifter cable to correct.
It also says the damper was installed on all Santa Fes beginning 12/21/02.
I would think this would apply globally, but I'm not sure. If you're
prior to that production date, then putting it on the shift cable may help
a little.

Check out the tsb on the web. It has many pictures. You can at least
look at the tsb and then look at your vehicle to see if the damper's
there. Go to www.hmaservice.com, select "service information" and "web
tech." On the next page, select "tsb" and 03 Santa Fe. Go to the
transmission section. You're looking for tsb 03-40-002.