How Tesla Keeps Changing the Model S—And Making It Pricier

In October 2014, Musk announced Tesla was installing the hardware needed to make its cars autonomous. A year later, it used a software update to turn on that capability, called Autopilot.

Right now, the Model S and X will stay in their lane (provided the hardware can see clear lane lines) and maintain a safe following distance. Plenty of people have pushed the system past its limits, but Musk promises it'll keep getting better.

When it hit the road in 2012, the Model S featured a single motor, which propelled the rear wheels. In October 2014, Tesla started offering customers the choice of a second, smaller motor to drive the front wheels as well.

The dual motor setup is a $5,000 option in the 70-kWh Model S, and included in the 90D and P90D models. If you're looking for acceleration, it's worth the extra money.

When Tesla started selling the Model S in 2012, the most affordable option came with a 40-kilowatt hour battery pack, for $50,000. Tesla killed the entry-level S within a year because no one wanted it. The next cheapest version, the 60-kWh Model S, died last year. Tesla replaced it with a 70-kWh model that starts at about $75,000.

And this year, Tesla replaced the 85-kWh battery pack in the range-topping Model S with a 90-kWh setup. The upside to steadily increasing the size of the batteries is cars with greater range (the 90D goes 294 miles on a charge). The downside? More expensive cars. So much for the "affordable" Model S Musk promised all those years ago.

Even with nearly 300 miles of freedom and an international network of Superchargers for powering up, it's hard to escape the range anxiety that comes with a purely electric car. To help out, last year Tesla used an OTA update to provide a "trip planner" and "range assurance" features.

Together, they noticeably improve the car's ability to estimate how much farther it can drive, and whether you need to plug in before reaching the destination you just popped into the navi system.

Like many high-end cars, the Model S can adjust its ride height on demand. In September 2014, Tesla used—you guessed it—an OTA update to introduce location-based air suspension. If you regularly raise the car in a certain place, like your driveway, the car will recognize the pattern and tweak the suspension automatically when it's in the area.

Like range assurance, this feature illustrates how useful the ability to update software really is: Without any expensive changes or service center visits, Tesla can make driving more pleasant for all its customers.

The Model S has gotten nicer over time, but also more expensive. In 2012, you could get one for under $60,000. Now, the base price is $75,000, and Morgan Stanley estimates the average sale price is north of $100,000.

That's not a problem for a luxury sedan. But when it's time to sell the Model 3, with a base cost of $35,000, it matters. The 300,000-plus folks who've made reservations are going to expect all of the good changes Tesla will surely think up going forward. But they won't be so excited about Elon reaching deeper into their pockets.