[Doggie 1]

I'm noticing something in my new i30 that I never had in my previous one that I just thought I'd put out there for a bit of feedback on please.
There seems to be a little bit of slack in the drivetrain which is noticeable when you are driving along and take your foot off the accelerator.
I don't know how else to describe it, other than maybe a slight clunk or thud, but not so much heard as felt. 
It has been there from new and I thought at first it was maybe my being not familiar with the new car, but it is definitely there.
Any ideas as to what it could be?
I didn't mention anything to the dealership at the first service as I don't want to raise an issue that isn't definitive and have them stuffing around trying to fix something and maybe causing another problem.
Other than that the car is going great, love driving it. I've done 4,000 kms now in less than a month (took delivery on November 30th) and it appears to be going to consistently give over 1,000 kms per tank despite its slightly smaller tank size than the FD, as it's currently showing 5.0 l/100 kms (the worst I've had actually) and the DTE puts this tank at a projection of @ 1040. The others have been 1060 +.

[AlanHo]

Nothing noticeable on my car. In fact I saw your message just before I went out and I kinda focussed on your concern and tried to replicate it.

I did notice when in second and third gear if I get up to 3000 rpm and suddenly take my foot off - the deceleration is so strong and instantaneous it almost feels like a thud - but this cannot be felt in the higher gears.

It is interesting that your DTE displays such high figures - mine has never predicted more than (the miles equivalent) of about 980 km until the tank is almost empty then it starts climbing, keeping step with the miles driven. The most I have done on a tank is 1210 km.

[Phil №❶]

Let's see, does it only happen once, or each time you decelerate. How many times per trip, eg every time without fail or randomly. What are the weather and road conditions. How many pob. All gears or just 6th. Any extra info will help to formulate ideas. 

[2i30s]

its the crap engine mounts Dave,Ive had my i30 back several times and nothing has been found.  i thought i had a broken engine mount at first. 

[AlanHo]

The 2012 i30 has different engine mounts - they are fluid filled to improve the dampening of engine vibrations from reaching the body shell.

Perhaps they are too soft - and go solid on sudden deceleration???????

Just guessing - I truly haven't a clue.

[Doggie 1]

Thinking about it, I've only noticed it in 6th gear but I will try lower gears today.
Weather and road conditions aren't relevant.
Always just me on board but I'm sure it would still do it with others too.
It does it pretty much all the time. It's not bad and it doesn't feel serious, but perhaps something you would expect to be there on a high km car, not a new one.

[2i30s]

The 2012 i30 has different engine mounts - they are fluid filled to improve the dampening of engine vibrations from reaching the body shell.

Perhaps they are too soft - and go solid on sudden deceleration???????

Just guessing - I truly haven't a clue.

i think the mounts are too soft also Alan. its nowhere near as bad with the wife's auto cw,but the manual is very bad. 

[komaterpillar]

agree with 2i30s the engine mounts leave a lot to be desired. having a soft fluid filled mount may help with annoying harmonics at idle and cruising speeds but under heavy acceleration or deceleration they aren't much chop.

another thougth - maybe one of the mounts has ruptured and is now bottoming out when pushed hard either way (accel or decel) with little or no dampening effect.

[Doggie 1]

Brand new car though.
I wouldn't have expected that.