In North America and Europe, the old saying—"Win on Sunday, sell on Monday"—probably no longer applies.

That is, winning races over the weekend probably does little if anything to boost sales of passenger cars and light trucks, certainly not the way it did in the U.S. in the 1950s and 1960s.

But like owning an electric car, the FIA Formula E electric-car racing series has to be experienced to be understood.

DON'T MISS: 11 things you need to know about Formula E electric-car racing

Yesterday, following two and a half days spent at the waterfront Brooklyn track where the New York City ePrix was held, we went through the basics of the race series.

That helped us sort out our thoughts on why the series is important—not just for racing fans, who find to their surprise that it is actually real racing, but more importantly, for electric-car owners, fans, and advocates.

The most important reason is identical to that for "regular" (gasoline or diesel powered) racing: it pushes technology harder, and that feeds back into better production cars.

BMW to take over Andretti Formula E team for 2018/2019 season

In interviews with managers, engineers, and drivers among the teams associated with Audi, BMW, and Jaguar, a few themes emerged repeatedly.

One of them was that the pace of technology change is rapid, continuously evolving, and in some ways challenging to accommodate.

Another was that the expertise of the race-car designers is a work in progress, with new learnings literally every week—and changes in powertrain control software daily, if not hourly.

READ THIS: Formula E electric-car races expands carmaker list, Audi, BMW, and Jaguar included (Oct 2016)

That all means that the teams work closely with engineers from the production-car side of the house to swap expertise where necessary.

For BMW, that means a close relationship with the Andretti Formula E team, which will run its cars as the company's works entry in the series starting with Season 5 in 2019.

Jens Marquandt, head of BMW Group Motorsport, told reporters that its "electric-car development is blurred with Formula E racing," to a degree that happens in no other racing series.

2016/2017 Jaguar I-Type 1 Formula E race car

The ABT Schaeffler team working with Audi has the advantage of much longer experience with electrified drivetrains, given the company's lengthy string of Le Mans victories in its TDI Diesel Hybrid endurance racers.

The Jaguar Formula E racing proram, meanwhile, has Richard Devenport, who's spent 20 years in product development.

He called the company's racing and I-Pace electric-car development efforts "a technology partnership," noting that he "takes back relevant engineering" to the vehicle program and sometimes "the other way too."

CHECK OUT: How Formula E electric-car series could make road cars better (Oct 2016)

What that means is that, as racing improves the breed and the electric race cars get faster, more powerful, and more durable, those advances can be transferred right back to a growing number of new-car programs now in the thick of development.

It's notable that so far, those brands are solely European (Audi, BMW, Jaguar, with both Mercedes-Benz and Porsche rumored for the future) and Chinese (Faraday Future, Nio, and others).

The Koreans and those North American companies with serious intent to produce volume electric cars may want to take note.

Audi, BMW, and Jaguar provided transportation, meals, and hospitality to enable High Gear Media to bring you this first-person report.

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