Wow. Finally got the time to make comparison..
As some know that previously, I drove a 2014 Mazda 3 Skyactiv CBU and sold it 3 weeks ago to get a Honda Civic 1.5TCP.
Sidetrack abit, why I sold the car is because it was stolen in October last year.
When the car found in March, I was happy because against all odds, manage to found it but after drove for 6 months, realized the feeling is not the same anymore.
Some ask me what is the difference between the 2. Here's my 2 cent:-
Driving Position:
a. Driver side
Getting into Civic, feels slight different from Mazda 3. Because Mazda 3 with longer bonnet, sometimes is very difficult to maneuver through tight parking lots. I often got scratches on the side due to wrong estimation. And viewing from driver side doesn't helps. So if you park in tight spot, make sure you clearly know the length of the bonnet. Civic on the other hand is shorter and surprisingly, easy to maneuver and estimate the length.
Unfortunately, the side mirror of Civic has disadvantage. Due to no gap in between side mirror to door, I need to sit up straight to see whether I'm turning correctly, especially in tight corner, trying to avoid knocking the hump on side road. Mazda 3 on the other hand got a gap, which allows me to see the distance. This is good as you know Malaysian roads some doesn't have an sign indicator of the hum is.
Steering is good for both cars as both also with leather but I found the Civic stitching a bit rough. Maybe because of CBU, Mazda 3 feels refine and premium feel when holding, especially the stitching part. Instrumental panel is good for both cars, but Civic wins with digital instrumental panel. Side panels such as windows and door locks are different for both. Mazda 3 is tilted 45 degree to give the driver's finger easy reach the window buttons when resting on the door panel but at the expense of feeling cramp. Civic on the other hand is flat 180 degree, gives a "spacious" feeling. Although felt the same for space for both cars, my passenger felt the civic is more spacious (Maybe Civic remove the CD player?) and surprisingly, felt the car height is higher than Mazda 3.. Whaaaaaaat?
Infotainment is essential to modern cars, especially to connect Spotify of course.

But Mazda 3 HU is easy to use. The OS is simple, clean and requires 2-3 steps to access the apps. Civic on the other hand, requires more than 3 steps and sometimes, require user to select the command using touch screen. Although sounds simple, try the touch screen while driving above 60km/h, you noticed your finger aiming accuracy is a challenge. Mazda 3 on the other hand disable touch functions and require user to use the BMW I-Drive like knob. Also, it was easy and intuitive to maneuver the menu. Volume knob in Mazda 3 is simple and easy to reach. Civic on the other hand uses touch sensitive.. Cool but not really practical while driving.
b. Passenger Side
Surprisingly, Passenger claimed Civic is bigger and easier to sit on compared to Mazda 3. I don't understand why but sure is weird since Civic is lower. Rear sits for Mazda 3 is not match with Civic. No contest at all. Seat on the other hand, Civic feels hard while Mazda 3 feels soft, even my Mazda 3 was leather wrap outside, but feel comfortable. Civic is good but a bit hard..
c. Small features.
Civic offers remote start so you can warm up the engine and start the air cond. Sounds cool at first but after few try, decided not to because..

Mazda 3 offer I-Stop function that paused the engine when it detects stop. Personally, I prefer Brake Hold because I-Stop feels jerky, rough and can be annoying. Also, you need different batteries for I-stop and price can range to RM650 per battery, which last 20,000 km est. Even with my CBU with I-Eloop, didn't help much.
Navigation, Mazda 3 uses SatNav, which no idea what it is but Civic uses more familiar brand, Garmin. Although Garmin, I often uses Google Maps than Garmin because most places are not updated in navigation system.

Using Bluetooth connection to phone, I found Mazda 3 sound is clearer and crisp. Civic on the other hand sound blurry and distortion. Maybe because of CBU..
Walk-Away features is available for both cars. Mazda 3 has a shorter transmission for Walk Away and can be annoying. When I got down from driver side, walk until the back booth, it locks, causing me to unlock again. Civic has a further transmission, gives me more to go the passenger side.

However, the beep sound of lock, Mazda 3 is at the front bonnet, while Civic is on the rear bonnet.
So far, that's all but if ask me of engine performance, honestly, both feel the same but Civic feels more power because its a turbo.

However, I feel Mazda 3 is slightly more fuel efficient, pumping 41L, gives me 480-500km mileage with 90% on city drive (if you count LDP traffic jam as city) Civic on the other hand gives me 460-490km mileage with 90% on city..
Handling.. Mazda 3 wins.
So if you ask me, which is better..
That is a hard question. If you watch Youtube channel like Autoguide, Redline, Everyman etc. I think I'm same thinking..
Mazda 3 is for sporty, fun on cornering drive, whereas Civic is for daily, comfort drive.
That's all. Excuse me for my English.