It's time i did a writeup comparing Apple to Apple. This case is the current 1.8G Altis(4 yrs old) vs 1.8 Elantra(2 weeks old). Both in the C segment.

1) Size
You will be suprised with this. I did.
I took a ruler to measure the back seat width. Elantra is wider than Altis by 1cm!! (Altis is already wider than Civic). It's the black interior of Elantra that gives illusion it's narrower than Civic/Altis.
As for leg room. Elantra is on par with Civic.
Headroom loses out to both Civic and Altis, but if u lay down and relax, you can have all the legroom you want. I guess you cant have it all if you want sportiness together with headroom?

2) Design
Up till today i can still stare at the car park outside my house and wonder how amazing the designer team has done with this car    Design wise, this car will still be way ahead of it's competitors 5 yrs down the road in Malaysia. Remember that this model has been launched in US 2 yrs ago, and I still do not see any new cars that can beat it's design in foreign magazines. Mazda should be able to catch up soon I believe, provided they dont take the new Honda Civic way...

3) Features
Elantra wins hands down. I loved the nappa leather, GPS/USB/Ipod, auto light on/off, auto wipers(on/off/speed), NO WOOD Trim!! SMART entry!! Sunroof!! Dual aircond however is overrated. ISOFIX no chance to use it yet.
Altis wins in term of power fold mirror, tweeter, much better audio quality(antenna,speaker), boot will open up 30degress once unlocked, and a full spare tyre.
btw, Elantra 1.8 china mari audio unit SUCKS! radio reception bad, CD song play halfway will jump to radio channel, GPS keep prompting cannot read SD card etc. and the black push button cover fell off when i collect my car 
1.6 is better as using back original unit.

4) Drive handling
Elantra has stiffer,bumpier ride to accomodate better turning around the corner. Less body roll (Continental Maxcontact)
Altis is more on comfort but very huge body roll (Michellin XM2)
Both are on Torsion beam. I have no problem with it as Elantra is meant for comfort drive. If you want to race, go Mazda/Civic(Not the new Civic pls!)

5) NVH
Elantra wins hands and legs down. i have never expected a car can be so quiet.
It's so quiet now that i can hear any minor rattle coming out from the interior including the leather rubbing against leather 
Road noise and wind noise is much much lower than Altis even when hit 100km/h
Engine noise, Trust me , its on par between 1.8 Altis. Both are noisy.    Only thing is Altis is more responsive. This cannot be said with Elantra 1.6 however. During the test drive, it kept shifting like out of breath. and with the constant shifting, its noisier.
And they say Altis is more quiet than Civic. So go figure...

6) FC
The Altis i owned and trade in was 4 gears, but the exterior is the same as current design.
FC Elantra only slighthly better. I manage to achieve 400km per tank (90% highway driving and works within KL). For Elantra I can get approx 430km. I am not sure about the run in period as will be only doing the 1st service next week.

7) Value for money
Definitely Koreans brands(Forte/Hyundai). Japanese brands nowadays only selling by brand name and minimal feature. Even if Mazda, in order to get specs like this in C segment, you need to go MPS (approx rm130k)
Furthermore, new model japanese cars are increasing in price and reducing in features(Camry)/space(Civic). I have been a loyal fan of japanese cars for the past 10 yrs, and sadly its time to say goodbye.
Summary:
Problem is only some rattle noise from the dashboard i need to fix during first service.
I never dare to imagine that i now felt like upgraded to a BMW from Altis. Never regretted it once and never looked back since  

super like this pic





giving the ride a sportier look