The whole point of an autonomous car is supposed to be so that the driver can sit back and relax, right?

Well, it turns out not all such vehicles are created equal.

Google’s latest autonomous car is truly driverless, meaning the driver is free to take their hands off the wheel and maybe even text or read a book. If it weren’t for regulations, Google’s car wouldn’t even have a steering wheel or pedals.

Not so with Nissan, which has created an autonomous vehicle by heavily modifying a Leaf using a dozen cameras, along with laser and radar sensors and a ton of computing power. Add it all up and the car can tackle most driving tasks under ideal conditions.

But it’s definitely not in the category of a “driverless car.” A human being needs to be ready to take over at a moment’s notice, and likely will be called upon to do so. During a half-hour test ride with reporters last week near its Sunnyvale research center, our driver — Nissan autonomous vehicle head Tetsuya Iijima — either had to take the wheel or nearly did, half a dozen times. Everything from sun glare to an idled truck forced Iijima to have to drive the car himself. One time, the car failed to detect a red light and Iijima had to apply the brakes in a hurry.

https://youtu.be/5j7YXD1R6pg

Iijima acknowledged the technology is still “very immature” and just getting used to U.S. roads, but said he hasn’t had any accidents.

Every major carmaker is getting into autonomous driving in some form or another — it’s very likely the future of driving. Nissan has six of its current generation of autonomous vehicle test models — three in Japan and three now in the U.S. They were first shown publicly in October at the Tokyo auto show, and Thursday was the first time anyone in the U.S. had a chance to experience a ride.

While Ford has been testing self-driving cars for years and other carmakers are putting semi-autonomous features into production models, Nissan is now looking to take features from the test track into production. Last week, the carmaker pledged to add various autonomous features on at least 10 vehicles over the next four years. Starting this year, it will have cars that can autonomously stay in their lanes on a crowded highway. Multilane highway driving is coming by 2018, while 2020 models will be able to handle intersections and city driving.

The test car we rode in fits in that last category, though the early part of the drive proved there is a lot of work yet to do.

After a less-than-reassuring first few blocks on city streets, Iijima programmed the vehicle to head onto a nearby highway.

“We’re going on the freeway?” asked veteran technology reporter Rafe Needleman, fear palpable in his voice. Another reporter quickly put on her seat belt.

But the freeway turned out to be far more comfortable than the city driving; the car was able to merge on the freeway, drive the speed limit, change lanes and exit without trouble.

Where Nissan finds itself isn’t that surprising when you consider its approach to autonomy, which is to add features to its vehicles one at a time and to aim for mass-market vehicles.

The prototype Nissan showed to reporters can handle single lane and multilane highway driving, as well as city streets. It just can’t do it right all the time. Which is kind of a big deal if you are looking to hand the steering over to a car.

Compare this to Ford, which has been testing its self-driving cars for a while now and is set to tackle snow and other extreme conditions, or to Mercedes, which just announced a new E-class sedan headed into production that can not only take the wheel on highways but also automatically avoid collisions, communicate with other cars and brake ahead of an impending collision with a car or pedestrian.

Renault-Nissan CEO Carlos Ghosn says that he isn’t trying to build a fully self-driving car and that he doesn’t believe that is what drivers want. Instead, he said he is aiming for a car that can avoid most accidents while also allowing the driver to hand over control to the car at certain times.

“Our goal is not a car without a driver,” he said in an interview with Re/code. “It may be a very important objective for Uber, because it is their model.

Nissan last week also showed off a separate self-parking car, which fared much better. That model, which could be activated via a smartphone app, was able to park forward and backward, and stop for pedestrians, including when I bravely (foolishly?) jumped in front of it.

One of the biggest issues has been liability. What happens when a self-parking car bumps into something with no one in the car? Nissan isn’t looking to take on the financial responsibility, so it has paired self-parking to a smartphone app, with the user holding down a button while the car is parking, showing they are taking responsibility, even if they are not at the wheel.