small comfortable commuter, not too boring,

I know you said you don't really want a new car, but I was thinking the redesigned Corolla would be a good choice. It rides on the TNGA platform, which is their newest platform. You get a lot for your money with that car. I'd only suggest the SE, XLE, or LE Hybrid trims.

Really, another Mazda3 would fit the bill perfectly. 2019 Mazda3 Sedan with the Preferred or Select package. The Select package with AWD MSRPs for $24k. You will be blown away by how nice the interior is. Hatchback is a $1000 premium. It is the closest car you can get to your needs. It is night and day between your 2016. It is now one of the quietest cars in the class. The powertrain is the carried over 2.5L with the 6 speed, so reliability should be very good despite being the first year of the redesign.

Also, what trim is your Mazda3? My son is looking to replace the tires in his 2015 i Touring sedan and he is looking at thePirelli Cinturato P7 All Season Plus. He wants a quieter ride, but still wants to preserve the steering feel and efficiency. I think anything would be an upgrade from the OEM Yokohama S34s, which lose 10 psi every couple of weeks and are very loud.

if you want a quieter interior, skip the hatchbacks. All of them are intrinsically noisier than a sedan, just because the interior is open to the cargo area.

A Corolla sedan would be my suggestion, a friend of mine has a 2018 or 2019 model and (surprisingly for a Toyota :-)) it does not have a bland interior while it does have tons of rear seat leg room (comes handy if you have to fit a car seat).

Another option worthy of consideration is theToyota Yaris iA, which is actually a rebadged Mazda2 (no longer sold by Mazda in US). Smaller and less expensive than a Corolla and it should be quieter than the hatchback model.

I have a 2017 Mazda3 Grand Touring Manual with the Premium Package and absolutely love that car, but you already have one so...

Check out a 2018 Hyundai Tucson 1.6T. A family member bought a new 2017 when it came out and it's been great so far. It's part of the reason I ended up buying a Hyundai Kona as my second car.

The Kona would fit the bill for all the mechanical and safety features you'd want. The DCT is a little but different than standard automatic, but no manual input is needed. The one caveat is the road noise of the Kona isn't particularly great, but so far that's been its one and only downside. You can get a new 2019 Kona in your price range. The 1.6T is worth the added premium.

The 2019 Tucsons don't have the Turbos anymore which is a shame since that's a very zippy engine that gets good mileage and performance. I'd even look into using ethanol-free premium as I do. It gets better mileage and performance.

From what I've seen almost everyone on my street has the same combo:truck + small car. Most of the trucks are like mine F-150 and most of the small cars are some type of Hyundai or Mazda 3.

Something really out there is a Mercedes B-200. It's oddly realible for a Mercedes and has lots of room. Depreciation is your friend in this case when looking for a used one.

This is a late response, but the Tucson DCTs had a decent amount of problems. That's one of the reasons why they stopped putting it in the Tucson. Another reason is that DCTs don't perform well in slow bumper to bumper traffic and that is where most Tucsons end up; not at the race track. If you aren't in traffic often it's a good choice in most cases.