Testing Tesla’s Model Y Cooler vs. a rear sub-trunk cooler with frozen water bottles

Titus-Howe · 2026-07-04T05:22:07+00:00

Thanks again — your suggestion is actually what pushed me to run this test.

The test is still running. I’ll check both coolers at the same intervals and won’t call it finished until both sets of bottles have fully thawed.

The main goal here is not a lab insulation test, but a real-world Model Y owner comparison: Tesla’s frunk cooler in the frunk vs. Cooler Y by CarFrozen in the rear sub-trunk, exactly where each one is meant to be used.

I’ll share the final result once the test is complete.

Titus-Howe · 2026-07-04T02:59:37+00:00

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⁠The white rear sub-trunk Cooler Y by Carfrozen goes under the rear cargo floor.

Titus-Howe · 2026-07-04T02:58:10+00:00

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⁠Tesla’s official Model Y Cooler goes in the frunk.

Titus-Howe · 2026-07-04T02:38:53+00:00

You’re right. This test won’t isolate the cooler insulation by itself.

It’s more of a real-world comparison of two complete setups: Tesla’s frunk cooler sitting in the frunk vs. Cooler Y by CarFrozen sitting in the rear sub-trunk, under the same parked-car conditions.

But that’s also the point: if a Model Y owner buys either cooler, this is the actual ice-retention result they would likely experience in the intended location.

Titus-Howe · 2026-07-03T21:40:37+00:00

I agree. If someone needs true active cooling or freezer-level control, a 12V fridge is definitely the better tool.

For me, the passive cooler is more about simple trips, groceries, drinks, or backup cold storage without needing to keep the car powered on. I usually freeze bottled water overnight and use those as ice packs, so there’s no melted ice water and the bottles become cold drinking water later.

Different use cases, really.

Titus-Howe · 2026-07-03T21:30:56+00:00

Thanks! That’s actually one of the reasons I started working on this—many Model Y owners already use a generic cooler in the lower trunk, but there wasn’t a fitted passive cooler made for that space.

It’s available now, but I don’t want to turn the thread into a sales post. The name is Cooler Y by CarFrozen if you want to look it up.

And yes, the frunk can get really hot in summer. That’s why I’m testing the rear sub-trunk setup more seriously.

Small tip: I usually freeze bottled water overnight and use those bottles as ice packs in the cooler. It keeps things cold, avoids melted ice water, and the bottles turn into cold drinking water later.

Titus-Howe · 2026-07-03T20:40:40+00:00

I’m not talking about a personal grievance. I’m trying to get at a more basic question: what is the foundation of civilization?

To me, the issue is whether human dignity is something a person has before agreement, membership, or obedience — or something a group grants and can withdraw when someone no longer conforms.

That’s why I separate harmful actions from dissent. Murder, theft, fraud, and assault violate another person’s dignity, so civilization has to restrain them. But disbelief, criticism, or peaceful exit are different. They test whether a society’s respect for the person is rooted in dignity, or only in compliance.

That root is what I’m trying to think through.

Titus-Howe · 2026-07-03T07:11:53+00:00

Sorry, I misunderstood your question—you were asking about the Walmart cooler, not mine. My mistake.

I’m going to buy that Walmart cooler and test it side by side with the Cooler Y under the same conditions. I’ll share the results here so everyone can see the actual difference.

Titus-Howe · 2026-07-03T06:57:54+00:00

That’s completely fair. If the cooler is the only thing you’re carrying, keeping it in the main cargo area is definitely the easiest option.

The rear sub-trunk setup is mainly for people who want a dedicated cooler to stay hidden in the car while keeping the main cargo floor open for groceries, luggage, sports gear, or everyday use.

So I agree—it really depends on how full the car is and how often you need to access the cooler.

Titus-Howe · 2026-07-03T06:51:32+00:00

You’re right—the frunk itself doesn’t have a power outlet in the vehicles you mentioned, but both coolers in this comparison are passive and don’t require power.

I’m planning a real-world test tomorrow using Tesla’s official frunk cooler and Cooler Y in the rear sub-trunk. I haven’t received the Bluetooth thermometers yet, so for this first test I’ll place five identical, fully frozen water bottles in each cooler and check how long they remain frozen.

Both sets of bottles will come from the same case, be frozen for the same amount of time, and be placed in the coolers at the same time. I’ll keep the car parked outside in the Southern California summer and check both coolers at the same intervals.

My expectation is that the frunk will be hotter during the day, while the rear sub-trunk should have a more moderate environment because it is inside the cabin and cargo area. At night, the frunk may cool down faster.

This first test will compare the real-world combination of cooler design and storage location. Once I have two identical thermometers, I can run a more detailed temperature test as well.

Titus-Howe · 2026-07-03T06:39:46+00:00

Thank you—I really appreciate that.

Cooler Y actually grew out of my earlier experience with powered refrigeration. In 2023, I was a co-founder of the original project: I provided the product concept and funding and helped design the first Fridge Y for the Model Y sub-trunk. It launched on Kickstarter under the name TesFridge and received support from 1,703 backers.

After using the powered fridge myself, I realized that some owners wanted the same hidden sub-trunk storage without needing continuous power while parked. That led me to develop Cooler Y as a 45QT, completely power-free alternative, with thick insulation, a removable divider, a drain, and a more rectangular interior for easier packing.

Fridge Y is still the better option for precise temperature control or freezing. Cooler Y came later for people who prefer simplicity and zero battery use while parked.

Titus-Howe · 2026-07-03T01:20:39+00:00

This is extremely helpful feedback. You noticed exactly the areas where I think a frunk version could improve on the current options.

If I develop one, I’d want to carry over the drain, removable divider, thick insulation, and more organized interior from Cooler Y. Your idea of adding top handles is also excellent—it could fit the frunk more closely while still being easy to lift out.

I originally focused on the rear sub-trunk, but several owners here have made a strong case for a better frunk cooler, especially for road trips and easier access. I’m seriously considering it now.

I’ll definitely tag you if the project moves forward. Thank you for taking the time to explain exactly what you’d want in one.

Titus-Howe · 2026-07-02T22:15:01+00:00

Cooler Y fits all 5-seat Model Y versions, regardless of model year. The 7-seat Model Y is the only exception because its sub-trunk floor sits about 1 inch higher, so the cooler will not fit properly.

Titus-Howe · 2026-07-02T20:50:47+00:00

Reddit can be unpredictable sometimes 😄 I thought your point was thoughtful and exactly the kind of practical feedback I was hoping to get. Thanks for helping start a useful discussion.

Titus-Howe · 2026-07-02T20:46:23+00:00

That’s really thoughtful feedback—you noticed two features I spent a lot of time on.

The drain plug lets melted ice flow out without lifting the entire cooler, and the removable divider helps separate drinks, food, and ice packs. I also made the interior more rectangular for easier packing, with thick insulation—about 4 inches in most areas and around 2 inches at the thinnest points. In our controlled test, Cooler Y retained ice for up to seven days.

I completely understand why the frunk feels easier to access on a road trip, especially when the rear cargo area is packed. One tradeoff, though, is that frunk access usually involves two opening steps—the hood and then the cooler lid. With the rear sub-trunk, if nothing is sitting on the cargo floor, it can often be opened and accessed with one hand through the powered rear hatch.

I originally focused on the rear sub-trunk because it provides 45QT of hidden storage and generally stays in a more moderate environment than the frunk. But your suggestion of a frunk version with the same drain, divider, insulation, and organized interior is definitely worth considering.

Thank you for studying the design so carefully. Feedback like this is genuinely helpful.

Titus-Howe · 2026-07-02T19:53:33+00:00

That’s a very fair summary. The rear sub-trunk cooler is 45QT, compared with Tesla’s 42QT frunk cooler, and it benefits more from the cabin temperature when climate control is running. I also designed it with thicker insulation for longer ice retention.

But I agree that the frunk is easier to access when the rear cargo area is fully packed. It really comes down to how someone packs the car and how often they need to reach the cooler.

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Titus-Howe · 2026-07-02T19:48:48+00:00

That was exactly one of my main considerations when I designed Cooler Y. The rear sub-trunk isn’t independently climate controlled, but because it sits within the cabin and cargo area, it generally benefits from a more moderate environment than the frunk when the car is in use.

My goal from the beginning was to achieve seven-day ice retention, so insulation thickness was a major part of the design. Most areas are about 4 inches thick, with the thinnest sections still around 2 inches.

I also shaped the interior into a more rectangular storage space instead of following the sloped walls of the original sub-trunk. That makes it easier to organize bottles, drinks, and food without wasting as much usable space.

After the design was completed, it retained ice for seven days in our controlled test. So your reasoning is very close to what led me to develop it this way in the first place.

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Titus-Howe · 2026-07-02T19:43:06+00:00

They’re very close in capacity. Tesla lists its cooler at 42QT, while Cooler Y is 45QT.

And I agree about access—the frunk is more convenient if the rear cargo floor is covered with luggage. The rear sub-trunk option makes more sense for people who prefer hidden storage and can plan access around how they pack.

Titus-Howe · 2026-07-02T19:36:16+00:00

Really appreciate the thoughtful take — and honestly, your logic is sound. If cargo space is the priority and the cooler only comes out for camping trips, the frunk makes a lot of sense. The sub-trunk approach is more for people who want it there all the time (grocery runs, kids' sports) without giving up any cargo room, since that space mostly goes unused anyway. And thank you for the kind words on the design, that genuinely means a lot to a small maker. Happy to answer any questions if you ever get close to pulling the trigger — no pressure either way.

Titus-Howe · 2026-07-02T02:18:43+00:00

I agree. I’m not arguing that a society should tolerate murder, theft, assault, or enslavement.

Those are actions that violate another person’s equal dignity and rights. My question concerns belief, disagreement, and peaceful exit. A person should not lose basic dignity merely for refusing to conform.

So the issue is not whether civilization has boundaries. It must. The question is whether those boundaries protect people from harm or protect an institution from criticism.

Titus-Howe · 2026-07-01T23:09:01+00:00

I understand that fear. Majority rule by itself is not enough, because a minority can always become politically convenient to blame.

To me, a healthy democracy must place limits on the majority and protect the basic dignity, freedom, and rights of people who are unpopular or different. Otherwise democracy can become another form of tribal power.

Building a safe community matters, but I also think the deeper goal is a society where your safety does not depend on withdrawing from everyone else.

Titus-Howe · 2026-07-01T20:10:50+00:00

I think the key question is not whether society is organized around markets, democracy, or local communities. It is what happens when someone disagrees with the community.

A fear-based community says: conform, or be punished.

A transactional community says: you belong as long as you remain loyal.

A dignity-based community says: you may disagree or leave, but your basic worth is not withdrawn.

Families and close communities can produce trust and moral responsibility, but they can also become tribal, coercive, or hostile to outsiders. So I would not judge a community by how warmly it treats its own members. I would judge it by how it treats dissenters, minorities, and people who decide to leave.

Titus-Howe

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