On the bass going missing in the car: that's very common, and it usually comes from two things working together. Headphones reproduce deep sub that car speakers and small speakers barely move, so if most of the bass energy sits below about 60 Hz it can all but vanish away from headphones. A dynamic EQ or multiband processor set to tame the low end can make it worse, because it pulls the bass down exactly when it's playing hardest. Taking it off the bass was a good call.
A few things that help it translate:
1. Give the bass some upper harmonics. A touch of saturation, or a filtered layer an octave up, adds content around 100 to 300 Hz, so the ear still hears the bass line on speakers that can't reproduce the fundamental.
2. Check it in mono and at low volume. If the bass drops away in mono, something in the low end is too wide or out of phase. Keeping everything below roughly 120 Hz in mono fixes most of that.
3. Use a reference track in the same style and flip between the two at matched volume, on headphones and in the car. It's much easier to judge your low end against something you know translates.
On reverb control, the trick that helps most is to keep reverbs on sends rather than on the channels, so you can treat them as their own parts of the mix:
1. Duck the reverb return with a sidechain compressor keyed from the dry signal (or from the kick). The tail stays out of the way while the part plays and blooms in the gaps, which keeps the essence without the flood.
2. High-pass the return at around 200 to 400 Hz and roll off a bit of top. Most of the mud comes from low-frequency reverb.
3. Add some pre-delay (20 to 60 ms is a good start) so the dry attack stays clear in front of the tail.
4. Automate the send level and the decay time with the arrangement. Longer, wetter in the breakdown, then pull both back as the drums and bass come in. Even a few dB less send in the busy sections makes a big difference.
Good luck taking it past the intro.
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