What’s happening: Nvidia this week released its new Drive Constellation simulation platform, which allows developers to play with variables like the angle of the sun, types of street lights, weather, road conditions, traffic and pedestrian behaviors.

• Rather than having a fleet of 50 or 100 AVs on the road, developers can test thousands on a virtual proving ground at the same time.
• Toyota Research Institute-Advanced Development is the first customer. It plans to simulate the equivalent of billions of miles of driving in challenging scenarios.

How it works: The cloud-based platform contains two servers operating side-by-side — one simulates sensor output from the car and the other receives that data, makes decisions, and then sends commands back to the simulated vehicle.

• Developers can create all kinds of scenarios — for example, an AV reacting to another car cutting into its lane in heavy traffic during a foggy night on wet roads.
• They can run the same test under other conditions simultaneously, completing months or years of testing in a fraction of the time.
• During a demonstration at this week's Nvidia GTC conference, I joked with a company engineer that he was playing God each time he hit a switch to change the driving conditions.

Waymo has driven more miles than anyone — 10 million on real roads and 7 billion on virtual roads, using its own simulation technology — but even that's not enough, based on research by the Rand Corporation, a policy think tank.

• AVs would have to be driven hundreds of millions of miles and sometimes hundreds of billions of miles to demonstrate their reliability in terms of fatalities and injuries, per Rand.
• Under even aggressive testing assumptions, it would take tens and sometimes hundreds of years to drive these miles with existing fleets.
• Developers "cannot simply drive their way to safety," the report found.

I heard a lot about simulation this week in Silicon Valley from all the major AV companies.

• "You have to lean into simulation to create these scenarios you never saw in the real world — but you might have," Sterling Anderson, co-founder of Aurora Innovation, told me.
• Simulation also gives developers the confidence to tackle edge cases that are too dangerous to test in the real world.

The catch: The simulation has to be a faithful representation of what would have happened in the actual vehicle. If the timing is off by even a micro-second, it can change the outcome, Anderson said.

The bottom line: Real-world testing still matters, as I learned riding around San Francisco and Silicon Valley this week in a variety of test AVs. Every on-road encounter unlocks new scenarios for developers to manipulate virtually in search of the perfect driver.

• The consortium will establish standards for odor measurement in AVs and create a reference database for smells that includes everything from cigarettes to fuel leaks.

Why it matters: When drivers give up their personal cars and instead become passengers in unmanned AVs, their ride experience could be determined, in part, by whether fleet operators are properly maintaining those cars.

Humans can sense an average of 1 trillion odors, according to the journal Science, so cataloguing them in a database could take some time.

• My thought bubble: I'm guessing nobody wants to smell any of those trillion odors in an autonomous vehicle.

Go deeper: Trump hates "crazy" driverless cars

Over many months, Axios has interviewed industry executives about Trump's policies and other sources who've discussed the auto industry with the president.

As with most relationships, it's complicated:

• Automakers hated being used as political punching bags during the 2016 campaign — Trump berated Ford on Twitter, for example, about building cars in Mexico and often got his facts wrong.
• After the election, they were generally pleased by Trump's attention to their issues, but not always with his actions.
• Corporate tax reform was a welcome boost, but then his steel and aluminum tariffs wiped out much of their tax savings and drove up car prices.
• Economists predict a sales downturn this year.

Now Trump is threatening to slap 25% tariffs on imported vehicles and car parts — which no one in the industry has asked for. As we've previously reported, most of Trump's senior economic advisers — with the notable exception of Peter Navarro — think new car tariffs are a terrible idea.

• But Trump tells everyone who'll listen that the threat of car tariffs is his best leverage in talks with foreign leaders.

Trump's bargaining chips have expensive implications for the auto industry — and for consumers. Ford CEO James Hackett said last September that Trump's steel tariffs would cost the automaker about $1 billion in profits.

• New tariffs would hurt auto suppliers, car dealers and U.S. factories that depend on global supply chains.
• Toyota, which promises to spend $13 billion to expand U.S. manufacturing by 2021, warns that Trump's tariffs would raise the price of a U.S.-built Camry by $1,600.

"There are 137,000 Americans who design, build, sell and maintain American-built Toyota vehicles. They deserve to know if they’re a security threat. And consumers need to know if their costs for American-made vehicles are going to go up."

Over the past two years, Trump has latched onto all kinds of ideas he thought would help the car industry. But the auto industry asked for almost none of them.

One backdoor move that died: making foreign car companies adhere to higher fuel economy standards than American companies.

Unwinding Obama-era fuel economy standards is popular with conservatives, but the auto industry is wary.

• Automakers welcomed the regulatory review, saying Obama’s higher standards would be tough to meet and didn’t match consumer demands.
• Publicly, they say they're open to gradual increases. But privately, some welcome Trump's rollback, according to several sources.
• Now Trump is battling California over the issue, as the state fights to set its own stricter standards.
• Automakers’ top priority is ensuring the U.S. has only one nationwide standard.

The bottom line: "There's political uncertainty everywhere you look, which is worse than any technological uncertainty because it has a chilling effect on investments," John Bozzella, president and CEO of the Association of Global Automakers, told Axios.