The gullwing-door is one of the most curious vehicles in the Japanese automaker’s history, and most of that can obviously be attributed to its nifty entry system. You might not be surprised to learn that as a product minted in the throes of Japan’s of the late ’80s, the Sera’s doors weren’t its only noteworthy trait.

Today we’re going to home in on one of the Sera’s optional features that’s often overshadowed by the whole door situation: the car’s Super Live Surround Sound stereo. SLSS was a 10-speaker system, which doesn’t especially sound like a lot until you consider that the Sera is so small it barely has back seats.

Toyota mounted a trio of tweeters in the dashboard, along with a cone in each door. Aside from a “Kelton-type Acoustic Resonance Woofer” in the the trunk contributing some necessary bass, the other four speakers comprised a pair of tweeters and cones inside a soundbar-looking contraption mounted atop the parcel shelf, directly under the hatch window.

This bar was the centerpiece of the SLSS system — you couldn’t miss it. Adorned with futuristic yellow text and lots of lines, denoting cryptic capabilities like “CASUAL MODE” and “FUNKY MODE,” this gizmo would look far more suited on a mech in Neon Genesis Evangelion than inside a flashy but ultimately unexciting-to-drive Toyota compact.

To get the most out of these speakers in the back, you’d want to familiarize yourself with a button in the car’s head unit with yet another nonsensical label: “WARP.” Press it and you’d cycle through the two modes of the SLSS digital sound processor or turn it off entirely. These are the Casual and Funky settings mentioned earlier, and they altered the presence of audio in the car by “artificially [adding] reflected sound.”

What’s especially interesting is how SLSS achieved its unique tones. Bass and treble are modulated as you’d suspect, but the Sera also pivots the speakers in that bar — Toyota called it a “rear loudspeaker” — to change the angle at which they project audio.

In Casual mode, the speakers fire more or less directly toward the passengers. But in Funky mode, they rotate to face the concave interior of the hatch window. The rationale was that this would lend a dash of reverb to the mix, supposedly conveying the live performance acoustics Toyota was touting.

Toyota partnered with electronics company Fujitsu to create the SLSS system. In 1991, Fujitsu Ten — a division now owned by Denso — published an flush with delightfully esoteric illustrations that explain the thinking behind the SLSS tech. The foreword, written by Toyota chief engineer Mikio Kaneko, is so earnest that it’s convinced me SLSS was and still is the most prodigious breakthrough in the history of car audio, even though I’ve never heard it in action and likely never will:

When the vehicle development had proceeded to the final stages, a demonstration onboard for well known audio journalists, was scheduled. One day before the demonstration, however, the intended sound could not be reproduced. Fujitsu Ten and Toyota’s engineers worked hard trying to find the cause, but could not. I was feeling uneasy but could only stand there doing nothing. Late into the night, the cause was found to be improper installation of the right and left speaker. The next day’s demonstration was very successful, the system was highly praised by the journalists as a milestone in car audio field. For the people at Fujitsu Ten and Toyota, it must have been a very satisfying day.

What a life-affirming story of crisis and perseverance. Not to mention one that was especially significant to Toyota, which was working tirelessly to appear hip and exciting to young customers in Japan around this time. The document contains a table titled “Characteristics of Young People,” including traits like “eat and dress well,” “want to be someone else” and “like the unusual.” “Music is an essential part of life for young people,” the background portion of the paper reads, indicating that the SLSS system was as core to the Sera’s youthful ethos as its distinctive doors.

SLSS-equipped Seras are evidently “highly sought after” — at least according to — making them an even rarer, more desirable version of a coupe you’re guaranteed never to see outside of your next trip to Radwood. Given that it’s unlikely most of us will ever hear what SLSS was capable of, we can be thankful that Fujitsu described the intended effect in its literature by painting quaint scenes with flavorful adjectives.

“Casual mode best suits music with a beautiful melody,” the paper reads, likening the sensation to sitting in a “modern concert hall.” Meanwhile, “Funky mode best suits music with a beat rhythm.” The company compares the experience that mode offers with “being present at waterfront concert” — an inarguably funky activity I’m sure everyone reading this can relate to.

Welcome back to Cars Of Future Past, a new weekly series here at Jalopnik where we flip through the

The enthusiasm Toyota and Fujitsu clearly had for SLSS is so palpable. For that reason, I’d like to end this exploration into the weirdest and most wonderful corner of car audio history with one more quote from Mr. Kaneko:

When territory and colleagues are chosen too rigidly, it is difficult to work to a new set of values. A new alloy can be created by combining different ideas and characteristics.

We expect to have more “FUNKY” shocks.

I can’t speak for anyone else, but bubble-era Toyota can always threaten me with a good time.