Why all future Sports Cars will be Electric Vehicles


Welcome to another Two Bit da Vinci Video. Today we’re talking electric cars, but not
in the way you’re probably thinking. When it comes to EVs most people think about
how efficient and better for the planet they are. We will cover this in the future, but today,
we want to talk about if EVs are actually more dynamic and better to drive than their
Gasoline counterparts. If you look at the design philosophy of something
like a Tesla Model 3, you get a glimpse into the future of the automobile. There is no driver gauge cluster, there are
barely any controls at all. Tesla is giving you a look into the future
where humans won’t be the ones doing the driving. Soon that steering wheel will be replaced
with a laptop tray or beverage holder. But realistically, that fully self-driving
future, is still over a decade away, for regulatory reasons if nothing else. So until that time, we humans will be the
ones doing the driving, and the question of how EVs handle and perform will remain important. So let’s break down EVs in the following
categories: 1. Aerodynamics 2. Weight Distribution and Center of Gravity 3. Engines vs. motors 4.Transmissions and power delivery. Let’s start by looking at aerodynamics,
where the main difference is one that we’ve all gotten so familiar with that we’ve begun
to see it as a feature, and not a flaw. That is a car’s front grill. Internal combustion cars need big front grills
for air intakes, to feed their engines, and radiators to cool those engines. Internal combustion cars aren’t very efficient
and over 50% of the burnt fuel is wasted as heat and noise. In contrast, EVs are between 80-90% efficient, and therefore require less frontal area for cooling. Many of our commenters have called the Tesla
Model 3 “ugly” because of the lack of a big grill in the front. Big front grills on cars are becoming an anachronism,
but many EVs still feature fake grills, just because people are so familiar with them. BMW sports their iconic kidney grills, while
Lexus has their controversial spindle grill. However you may feel about these styling cues,
they’re bad for aerodynamics. Now it would take many years of engineering
school to fully understand aerodynamics, but let’s give it a go. To understand the ideal aerodynamic design,
we need look no further, than mother nature. The raindrop, pulled by gravity, fighting
air resistance, naturally takes the forms of the perfect aerodynamic shape. The leading edge is rounded to shed air in
every direction, with minimal flat spots causing stagnation. The trailing edge tapers to a near point,
allowing all the redirected air, to stay connected as it travels, and ultimately converge at
the end. This explains why all commercial airplanes
look, more or less the same. Ok so why is the rounded nose so important? Well let’s see what a rectangular box would
look like in a wind tunnel, in comparison. Because there’s a big flat spot in front,
there is going to be a stagnation point, where the air comes to a grinding halt. This is really bad, like air hitting a sail,
and pushing it back. But it gets worse because this stagnated air
causes a high-pressure region, that pushes the flow around the rectangle further out,
instead of right on the surface. This, coupled with the flat rear end of the
rectangle means the diverted air must travel much further before converging again. To understand why this is bad, let’s think
about drinking a beverage through a straw. What you’re actually doing, is sucking out
the air inside the straw, causing a vacuum, which forces the liquid up the straw in the
direction of lower air pressure. If you turn that analogy on it’s side, the
trailing end of our rectangle results in a near vacuum. This vacuum sucks the rectangle back, just
like the liquid in our straw. This is why cars like the Toyota Prius, or
the Porsche 911 have rear ends that taper down in a fastback style. Bringing this back to EVs, a smoother front
end will result in a lower drag coefficient. With Internal combustion cars, more air collides
with radiators and other bits in the engine compartment. Now it’s important to note that hydrogen
fuel cell cars are still electric, but they do need air intakes, to provide oxygen to
react with the liquid hydrogen. But this smoother front end, is the only real
advantage that EVs have. Any car can have smooth body panels, and increasingly,
more crossover SUVs have the swooping coupe-like design. But it does appear that EV makers like Tesla
obsess about aerodynamics more than other companies. Teslas have flush mount door handles, wind
tunnel tested side mirrors, and all their cars are top of the class when it comes to
aerodynamic efficiency. To put this in context, the biggest and bulkiest
Tesla, the Model X, has a drag coefficient of 0.24, while a similar Audi Q7 has a drag
coefficient of 0.33. So the smoother and less interrupted front
end of EVs helps with this, but to fully understand their obsession with drag coefficients, you
have to consider how costly it is to add range. Want 100 more miles of range in a gasoline
car? Just add about 30 lbs(13.6 kg) of fuel capacity. Want to add 100 miles (161 km) of range to
an EV, well that will cost thousands, and weigh hundreds of additional pounds of batteries. Tesla obsesses about aerodynamics because
it’s the best way to squeeze out every last mile out of their battery packs. Ok so EVs have a slight advantage in the aerodynamics
department, but how do they stack up against their internal combustion rivals when it comes
to overall vehicle weight, weight distribution, and center of gravity? You might be thinking that EVs have a disadvantage
here due to their heavy battery packs, and you’re right. But you have to remember the average petrol
car has an engine that’s around 400 lbs, another 150 lbs for the transmission, and another 100 – 200 lbs for the gas and gas tank In comparison, the Tesla Model 3 long range
has a battery pack that weighs 1000 lbs, and electric motors weigh about 75 lbs or 150
if you have dual motors. So internal combustion cars are usually lighter,
but what’s equally important is how that weight is distributed. The ideal weight distribution is evenly spread
left to right, front to back and as low to the ground as possible. The center of gravity, or center of mass is
a point in 3D space where all the mass to either side of it, is equal. To best understand this idea, let’s consider
a see-saw. If you have equal weight on either side, the
pivot point should be right in the middle, to balance both loads. However, if the weight on one side is twice
as heavy, that pivot point would need to move closer to the heavier mass, to balance the
two masses. This pivot point, in the see-saw analogy,
corresponds to the center of gravity. Early hybrids that were conversions from gasoline
cars, like the Honda Civic hybrid, have a poorly placed battery pack, usually under
the rear seat, or trunk. In contrast, pure EVs, purpose build from
the ground up, have battery packs that are placed evenly throughout the floor of the
vehicle. So even though EVs weigh more, this weight
is very evenly distributed, and very low to the ground. Petrol cars have a decision to make when it
comes to engine placement. Most cars have the engine in the front, mounted
transversely if its front wheel drive, and longitudinally if its rear wheel drive. More exotic cars, are mid engine, again in
an effort to put more of the big masses closer to the center. Electric cars have an advantage here, because
the heaviest part of the car, the batteries, are placed on the floor, and electric motors
are light in comparison. For maximum handling and cornering performance,
there are a few key elements. The first is having the center of gravity
as low as possible, and the second is weight distribution from front to back. The rollover angle is the angle from a line
drawn from the contact wheel to the cars center of gravity. This affects two things, the cars rolling
from side to side in turns, and also its tendency to pitch forward and back during acceleration
and braking. Sir Isaac Newton’s first law of motion is
that a body at rest, tends to remain at rest. This means as you start to turn, the car,
acting at its center of gravity, wants to keep going in its original direction. The higher the center of gravity is from the
wheel axle, the greater the body roll, and the easier it is to tip over. Let’s compare a hypothetical car with wheels
connected to just a rectangular chassis. In this extreme, the center of gravity is
in line with the wheel axles, which would totally eliminate body roll, and make it practically
impossible to roll over. In contrast, if you had a big off-roading
truck with a lifted suspension, the center of gravity would be much higher, and as a
result, the rollover angle increases, and the vertical component of the resulting roll,
puts a strong downward force on the contact wheels, and a lifting force on the opposite
wheels, rather like a see-saw. This is what causes cars to roll when turning,
and should be minimized as much as possible. For that “riding on rails” feel, you need
a very low center of gravity, coupled with a stiff suspension setup. Now let’s turn our focus from the front
of the car to the sides, where again the center of gravity comes into play. Applying the same roll angle principle, but
this time, instead of side to side, from forward to aft, we see a similar phenomenon. The roll angle is once again the angle between
the line joining the contacting wheel through the center of gravity. When you slam on the accelerator and speed
up, the inertia of the car’s mass wants to remain at rest, and will act in the opposite
direction of travel. This will cause the car to pitch up, putting
more downward force on the rear tires, and an upward force on the front tires. During braking, the opposite is true, the
car inertia wants to keep it moving, and the direction of the force points forward. The vertical component of this force pushes
down on the front wheels, and lifts up on the rear wheels. This is why cars always have bigger brakes
on the front wheels, than on the back wheels, and why most performance cars have rear wheel
drive. The added down force on the front wheels,
allows for a greater friction force on the front tires, and allows the brakes to exert
greater stopping force, than the rear brakes. For rear wheel drive cars, the added downward
force during acceleration, means greater normal force, greater friction, and greater traction,
to put the power down to the road, than front wheel drive cars. Now that being said, let’s look at some
CGz (or center of gravity in the vertical axis) of some different cars. The BMW 3 series, is one of the most popular
sports sedans around the world, and has a center of gravity of 20” (50.8 cm). But the electric BMW i3 beats it at 18.5”
(47 cm). The Toyota FT-86 or Subaru BRZ is praised
for its low CG of 18.1” (46 cm). Hyper cars are low CG champs, the Porsche
911 GT3 measures in at 17.9” (45.5 cm) and the Lexus LFA at 17.7” (45 cm). But one car that beats them all is the all-electric
Tesla Model S measuring in at just 17.5” (44.5 cm). The Tesla Model 3 will be quite similar, and
maybe even lower than the Model S. Weight distribution is a similar story, where electric
cars, with their batteries, spread evenly, deliver very close to 50/50 weight distributions
front to back. The Tesla Model 3 delivers a weight distribution
of 47/53 biased toward the rear of the car. This is very similar to performance cars like
the BMW 3 series. So while EVs do weigh more than their petrol
counterparts, they have great flexibility in design, don’t need big heavy engines,
and can deliver some incredible center of gravity figures.