Sooo I actually just saw this thread and honestly, as a fellow Mazda6 owner, the struggle with that deep trunk is REAL!! The technical issue here is the lateral G-force during cornering vs. the low-friction trunk carpet. Basically, you need a high-grip base or a heavy-duty strap system to keep things from shifting.

For your situation, I would suggest checking out the Starling's Car Trunk Organizer with Adjustable Straps and Non-Slip Bottom. It's a beast because it has 1680D Oxford polyester, so it's technically more rigid than cheaper nylon ones and won't collapse when it's empty. Plus, the non-slip pads actually bite into the Mazda's carpet pretty well.

Another solid option is the Honey-Can-Do SFT-01166 Large Trunk Organizer. It's a bit more minimalist but fits perfectly between the wheel wells of the Mazda6's layout. It's great if you want something that doesn't feel like a giant box taking up the whole space, but it lacks the heavy-duty tie-downs of the Starling's.

I mean, if you want total security, go with the Starling's because those straps are basically mandatory for spirited driving lol. Good luck!! 👍

Basically, you gotta look at Fortem Car Trunk Organizer or the Drive Auto Car Trunk Organizer. I've tried both in my Mazda and honestly, the Fortem is *solid* because it has a lid and straps, whereas the Drive Auto one is kinda better for quick grocery hauls since it's easier to reach into... but it might slide more if you don't use the tie-downs. Best bet is the Fortem for stability tho!

TL;DR: I found that using a budget-friendly collapsible bin with a sticky bottom works wonders in the Mazda6's deep trunk without breaking the bank.

Just sharing my experience: I went through this exact same thing last year when I first got my 6. Honestly, that deep trunk is a blessing and a curse!! I remember my first grocery run... heard a jar of pickles shatter against the wheel well after a sharp turn and I was just so done with it. Since I didn't want to drop a ton of cash after just buying the car, I spent a lot of time looking for something cheap but effective.

I actually ended up getting the Starling's Car Trunk Organizer with Adjustable Straps and it has been great. I think I paid like $30 or $40 for it? What I really like is that it's got these rubberized feet on the bottom that actually grip the Mazda carpet pretty well, even without the straps. Plus, it's sturdy enough that it doesnt just flop over when it's half-empty.

Another thing I tried was the Honey-Can-Do SFT-01166 Large Folding Trunk Organizer which is super budget-friendly. It’s a bit more basic than the stuff mentioned before, but it fits perfectly between those wheel wells. Honestly, I'm pretty satisfied with how it's held up over the last 10 months. No more runaway oranges or broken jars, which is a total win in my book!! Just make sure whatever you get has some weight or a good grip to it cuz that trunk floor is slippery lol. 👍

Seconding the recommendation above about getting something with straps! But seriously, before you buy anything, watch out for those cheap-o generic ones that don't have a solid bottom. I've been doing some market research (aka scrolling through reviews for hours lol) and learned that the biggest mistake is buying the ones that are just fabric without a reinforced base. If it doesn't have those hard inserts, it's gonna collapse the second you put a heavy gallon of milk in it, which is basically useless for a Mazda6 trunk.

I'm still kinda new to this car-mod life, but honestly, I found that the Starling or Honey-Can-Do brands are pretty decent value for the money if you're on a budget. They're usually way cheaper than the high-end stuff but still reallyyy sturdy. I mean, ur groceries shouldn't cost more to organize than they do to buy, right?? Has anyone tried the ones with the built-in cooler bags? I'm wondering if those actually stay put or if they're too top-heavy for corners. gl!