When you first start racing and paying attention to which cars make a difference, you'll see "FTE" and the phrase "Faster Than Ever" tossed around quite a bit. That might sound like just a marketing gimmick but there's a little bit of truth in the name.
Faster Than Ever
The "Faster Than Ever" or "FTE" cars are mainline cars (ie, the $1.00 variety) that were made with special, nickel-plated axles. The nickel made for a much shinier, smoother surface and thus this allowed wheels to spin a little faster thanks to some reduction in friction.
You might wonder if such a thing really makes a difference, and science-wise, yes, it does. A smoother surface means less friction which means less energy wasted which means more speed...or something close to that. But also consider that there are a lot of other factors that play into a car's speed beyond just the axles. When you consider things like weight, balance, wheel base, length and so on...the axles might not seem like a big deal but it's also a case of, "why not?"
When you're racing, you look for every advantage you can. So if you can get your hands on some shiny, smoother FTE axles, they certainly won't hurt...but the trick might be just finding them.
The FTE mainlines were produced between 2005-2006 & 2009-2010. It was often noted on the packaging that it was a "Faster Than Ever" car, but they can also be identified by their bronze open hole 5-spoke wheels. As of 2018, Hot Wheels no longer produces FTE-packaged mainline cars but that doesn't mean you can't find those nickel-plated axles. These special axles were used in more than just the FTE-labeled cars.
Where to find FTE axles
Even though the actual "Faster Than Ever" labeled cars were limited to a 4-year run, there were many hundreds of thousands of them made, so they're not exactly rare in the collecting way. You can usually find them in hobby stores and flea markets for little more than the original $1.00 price tag. They're not particularly hunted by folks other than racers, so at least you're not competing against collectors. Of course, eBay and online markets are full of them as well...knock yourself out.
However, the nickel-plated axles themselves were used in more than just the FTE mainline cars. These premium axles were used in some non-mainline runs of cars and are still being used in current retail releases, even if they're not the $1 mainline cars.
Here's a short list of Hot Wheels lines that also used the nickel-plated axles. Not all of these are in production anymore but you can keep an eye out for the package names.
So while you're most affordable bet is to just check out your local second hand source or online, if you're jonesing for a FTE axle, you can probably find one at Target or Walmart...just know you might spend a few more bucks.