Maybe that's your feeling. it's not on Vitz NBC Platform it's on Corolla platform. Weight factor is not sufficient for improving vehicle stability. As my experience, the older 141 Axio felt like the car is flying, when the speed is over 120km/h. The new 165 one is more comfortable and stable in higher speeds with improved aerodynamics and suspensions. Also, Vitz has very stiff suspensions and it's a city based car but new 165 Axio comes with comfortable softer suspension setup. Vitz is a Hatchback and it has 3945mm of length. Axio is a compact sedan and it's got 4400mm of length. Also there are big space inside with boot. Wheel base in Vitz has 2435mm, 165 Axio has 2600mm wheelbase same as older 141 Axio and Honda grace. Also, Both 141, 165 Axios have same width 1695mm. In that manner, there is no way to say the older Axio is bigger and new Axio is using Vitz resources. It's common dimensions for compact sedans. I was also thinking about this car as you're thinking but after using it I felt it's more improved when compared with older one. Overall comfort, handling, features, cornering, safety, acceleration, seats, climate control setup and lot more improved. Some people are still like older Axio for it's beachy interior like Allion. But it's dashboard and plastics are way cheaper and wear quickly than new model. The only negative side is new Axio is the center console is bit lower but it's not a big practical problem at all. it's also has better expert rating 7.9 out of 10. The 4th gen Prius is also rated 7.8. I was also unable to find any proper review for this car in youtube. Most of them are talking different thing to each other. I would like to say, First find a good condition vehicle and then drive it without listen to others. then you can feel what I'm saying. I'm not pointing this to you my friend. Don't judge by book it's cover. lol