Fast cars are usually a little wider. This helps them roll down the track a bit straighter and have less chance of bouncing around. Narrow cars have a tendency to be less stable and bounce around. When they are bouncing back and forth in the lane, the car is losing speed. Notice the width difference in these two cars.
To illustrate the instability point, check out this video of formul8r (a nice wide car) vs. The Porsche Outlaw (a fairly narrow car). You'll see the Porsche get into a "death wiggle" that completely kills it's speed.
Fast cars are usually heavier. Heavier cars have more potential energy at the top of the hill. That translates into more kinetic energy at the bottom of the hill, which translates into speed. Potential energy depends on the weight of the car and the height that the car is at. The cars will be starting at the same height, but a heavier car will have more potential energy. That means more kinetic energy at the bottom of the hill, and more kinetic energy means more speed. That extra weight will help the car keep it’s speed better in the flat stretch to the finish line.
When picking out a car, make sure that there is not any part of the car that will rub on the sides of the track. Often cars have running boards or other things that stick out on the sides. If these parts of the cars rub on the sides of the track, it will really slow the cars down. Also watch out for cars whose wheels are set in from the edge of the body. Even though these cars don’t look like they have anything sticking out on the side, the body itself will rub.
These two cars both have issues. The Plymouth's wheels are set in and the 40 Ford has it's wheels set in as well as a running board connecting the fenders.
Notice how both of them rub on the sides of the track. This rubbing really slows them down and makes them terrible racers. (Although to look at, this 40 Ford is one of my favorites!)
Make sure that the car doesn’t have an extra long length from the front wheel to the front bumper. Not a lot of cars have this problem, but there are some. If the car is low to the ground, that will exaggerate this problem. What happens is when the car comes of the hill, the front bumper can scrape on the track causing the car to slow down. The problem also becomes worse as the steepness of the drop hill increases.
This Corvette has this problem.
Because of it's long low front, as it comes off the hill, the front scrapes on the track and slows it down.
A car with most of it's weight in the back, all other things being equal, will be a faster car. Having the center of gravity - or more of the weight in the back - comes back to potential energy. Potential energy depends on height and weight. Let’s suppose that two cars have the same weight, but when it comes to gravity, it acts as if the weight is all in one place. We call that the center of gravity. The further back the weight is placed on the car, the further back the center of gravity. On an incline, that means the farther back the center of gravity is, the higher it is, which means more potential energy.
Check out this clip from a great pinewood derby video by Mark Rober. It helps explain this with some great visuals.
A low center of gravity will help the car be more stable and run straighter. As discussed earlier, if the car is bouncing back and forth from one side of the track to the other, your car is going to lose speed. One of the problems is that usually the cars with a low center of gravity are also thin, so they are lighter, which doesn’t help in the speed department.
A longer wheel base improves the stability of your Hot Wheels car, which translates into a smoother, straighter ride. Comparing a short wheel base to a long wheel base is like comparing a Corvette to a Cadillac. While the Corvette is quick and maneuverable the Cadillac gives you a very smooth ride. Since we are racing on straight downhill tracks, maneuverability is not an issue. We want a nice smooth straight ride.
In the previous example of comparing a Cadillac to a Corvette, I was referring to real cars, but let's see how the analogy holds up in the following example with Hot Wheels cars.
Having good wheels is important for speed. Some wheels seem to be faster than others. Faster Than Ever wheels are the best wheels, but they were only produced during a few production years. Right now there are no Faster Than Ever wheels on the shelves. Technically, it wasn’t just the wheel that made the Faster Than Ever cars fast. Most of it was due to the nickel plated axles that reduced the friction between the wheel and the axle.
However the open hole 5 spoke wheel that came on the Faster Than Ever cars is a great wheel and still comes on cars produced right now. Science also says it should be a great wheel. Once reason is because of the “open holes”. That makes the wheel lighter, which means that it takes less energy to get the wheel rolling and less energy to keep it rolling. That means more of that potential energy is turning into kinetic energy, and kinetic energy equals speed - Well, not literally for you scientists - KE = ½ mv^2 - but you get the idea:)
Another great wheel is the traditional 5 spoke wheel. I’m not exactly sure why this wheel seems to perform well, but it does.
Looking at the top fastest cars from 2015, I noticed another wheel that a lot of the cars had in common. The PR5 wheel. Five of the top ten 2015 cars had PR5 wheels. Four of the other 5 had open hole 5 spoke or traditional 5 spoke wheels.
A final note about wheels, medium to large wheels seem to generally help a Hot Wheels car be faster than one with small wheels.
So we’ve looked at quite a few things that can help a Hot Wheels car be fast. It’s pretty difficult to find all these things in one car without modifying it, and I’ve probably left the most important thing off the list. That is luck. When it comes to finding a really fast Hot Wheels car right out of the package, a little luck is involved. Yes, there are definitely certain castings which have an advantage and are generally faster than others, but all things considered, the wheels and axles are what are going to make or break your car. And that is something that you can’t check until you open it up and send it down the track. Most axles have burrs and imperfections on them, particularly on the ends. What you’re hoping for is an axle that has smaller burrs or less imperfections on them. Sometimes you just get lucky. In addition, almost every wheel has a mold injection spot on it, and you have to remember that mass producing and selling a car for $1 doesn’t encourage precision. Most wheels are not perfectly round and smooth. If you get lucky, you happen to get some wheels that are more round and smooth than others. If you get good wheels and good axles on the same car, you’ve got a winner.
This happens to be the case so far with our 2016 cars. After testing the first 32 cars, the Nitro Tailgator is our fastest car. However, I think this is a bit of an anomaly. While the Nitro Tailgator is a pretty good car, I decided to do a little more experimenting. I bought a few more Nitro Tailgators and a few more Corvette Grand Sport Roadsters. In each case the Corvette Grand Sport Roadster beat the Nitro Tailgator. It only seems to be the Nitro Tailgator that I tested in the official bracket that beats everything else. I got lucky and found a car with great wheels and great axles...and it is fast...way faster than other cars of the same casting.
Watch Nitro Tailgator pick of the competition in the following video.
So what do you think? Have you noticed any characteristics that make fast cars? Let us know in the comments below?