When it comes to talking about autonomous vehicles — which we’ve been doing a lot of, lately — it’s helpful to have some sort of guide to help everyone understand just what degree of autonomy we’re talking about. That’s why the Society of Automotive Engineers (SAE) came up with their . The to judge just how automated or autonomous (there’s a difference) cars are or aren’t. , and I think if we want something that any member of the public can easily understand, we need something else.

Luckily, I have an idea. And it involves napping.

First, let’s review the SAE chart:

Okay, so we have six levels here, numbered from zero to five (remember, they’re engineers) and there’s a lot of subtle differences between the levels.

Basically, it breaks down like this: anything Level 2 and below is not self-driving at all, and a human must be ready to take over at any moment. This is obvious for Levels 0 and 1, which are pretty much cars with no automation and basic cruise control, respectively, but things can get fuzzier for Level 2, the highest level available in widely-available production cars now, because while they can do a lot of the driving on their own, but they need a human to be ready to take over with minimal or no warning at all.

For example, when a Tesla on Autosteer is unable to detect a driver’s hands on the wheel, this is how it reacts, according to Tesla’s owner’s manual:

If you repeatedly ignore Autosteer’s prompts for having your hands on the steering wheel, Autosteer disables for the rest of the drive and displays the following message. If you don’t resume manual steering, Autosteer sounds a continuous chime, turns on the warning flashers, and slows the vehicle to a complete stop.

The car does come to a stop and turn on its hazard lights, but it’s not checking where it’s stopping. If this happens on a highway, it’ll stop in its lane, even if that lane is full of cars going 80 mph. It’s not a safe automatic handoff solution, which is why or watching a movie or whatever in a Tesla on Autopilot is such a .

Tesla’s Autopilot and GM’s SuperCruise are at this level. I think— — that Level 2 Automation is an inherently bad idea because the sort of vigilance tasks these systems ask of the human behind the wheel are not tasks humans are good at.

From Level 3 up, the crucial difference is that the car’s systems do not require a human to take over immediately — they have some means of handing off control safely, or getting out of harm’s way on their own if the situation demands it.

For Level 3, this can mean that when the car is not capable of continuing independently and may require human assistance, it can safely pull over to the shoulder or outermost lane if the driver doesn’t respond. Level 3 systems still prefer a human to be monitoring them, though, and if they cannot get a human’s attention when requested, will safely stop.

Level 4 can basically get by with one one paying any attention at all, but it can only do so in restricted areas that have been vetted to be safe for autonomous use.

Level 5 is the dream, an ideal robot car capable of doing everything on its own, except perhaps for deciding where to go.

That’s a lot to keep in mind, which is why I propose a new system, targeted at laypeople or car buyers who just, frankly, don’t really give a brace of B.M.s about how AVs work, they just want to know how little attention they need to pay to driving when in the car.

That’s why I came up with this instantly understandable autonomy rating system: The Z-Rating.

Basically, the Z-Rating system gives the answer to the question “Can I safely and legally nap while in the driver’s seat, while the vehicle is driving?” There’s only two answers to the question, yes or no, though “yes” does have a few basic qualifiers.

The name comes from the standard cartoon indicator of sleeping, the Z in a balloon. But you got that.

Here’s how the Z-Rating translates the SAE Autonomy Levels Chart:

What I’m thinking is that any car that has any sort of autonomy or semi-autonomous features would get a Z-Rating, and that Z-Rating will be either YES or NO, and if it’s YES, it may have one or more BUTs with it.

That’s it, though. No more confusing terminology, and if a carmaker insists on using names that are at best or at, there’s always a simple Z-YES or Z-NO to help keep consumers aware and safe.

I’d love to see the little Z logo and a YES or NO become an accepted icon that gets used all over. By this I mean I’d love for this (or, really something like this) to become a voluntary industry standard, so when you go to a website talking about a company’s AV offerings, you see something like this:

...or, another example, to be fair:

The addition of a clear, obvious, easily understood icon and rating like this would give buyers absolutely no question about the most important aspect of the autonomous or semi-autonomous system they’re researching: can I nap behind the wheel, yes or no.

The website can go into whatever details about features it wants, but the most fundamental limitations will be obvious and clear.

For something like Honda’s new Legend with SENSING Elite, (maybe with caveats, we’ll see), we would have something like this:

All still easy to understand. One glance, yes nap, but the car may stop. That’s the information you need to know. The Z-rating system will reduce the SAE chart to four possible ratings: Z-Yes, Z-No, Z-Yes But Car May Stop, and Z-Yes But Only In Certain Areas.

Most importantly, this system is easy. Everyone understands what sleeping in a car means. Everyone understands what yes and no are, and even the BUT qualifiers are simple.

The whole point is to eliminate confusion. Sure, there’s much more nuance to all of these systems, but when it comes to keeping people safe on the road by understanding the capabilities of these wildly complex systems, simplicity is the way to go.

Automakers, I offer you the Z-Rating system to use as you see fit. In fact, here’s all the icons you need, in PNG form, yours for the taking:

You’re welcome.