What Makes a Car Fast

Timeless Wisdom

I've often heard an outdated philosophical phrase stating that "There's no replacement for displacement." Enzo Ferrari once famously declared that Aerodynamics are for people who cannot build engines." Are such sentiments based in reality or are they ignorant? I suppose you could argue that there was a time that these ideas would have probably held true, but automotive technology has developed a lot over the past century. Well, really, it never stopped developing a great deal from day one, but a century ago these philosophies may have held true but do they now?

Replacement for Displacement

Let's start with a big one - displacement. I am American, and it seems that, at least based on the conversations I've personally had with fellow Americans, the infatuation with big engines and big power is central to their car performance philosophies. Do not get me wrong, here. I love a classic muscle car, and the rawness and throaty growl of their big engines. I appreciate that you can get several-hundred horsepower and a handsome car for a lot less money than you'd invest in a European sports car. However, that romantic love affair shouldn't get in the way of reality.

We're going to compare a handful of different classes of race cars here. Up front, we're looking at their engines - how much power are they getting from how much motor. Let's start with something more classically American. A NASCAR Cup car has a hulking 5.86-liter V8 engine producing up to 670 horsepower. If anything serves as a poster child for American muscle, it's something like this. I do appreciate their sound and that you can get a NASCAR Cup car for a fraction of the cost of other cars we'll look at. If we do the math, this motor is offering us about 114 horsepower per liter of engine displacement.

Later we will compare against GT3 machines, but here that will be more tricky because they vary quite a bit, including ranging from 3.0 liters to over 6 liters, and they vary by manufacturer. The same goes for WEC Hypercars, ranging from 2.6 to 5.5 liters, but an example of their productivity would be around 121 horsepower from the 5.5-liter engine. That's in the ballpark of that NASCAR engine, though slightly more efficient. IndyCar has a much more modest engine volume, running a 2.2-liter V6. Typical American perspective would expect that to be crushed by the more massive, mightier NASCAR motor. However, that little 2.2-liter V6 produces upwards of 700 horsepower, or around 318 horsepower per liter. That's approaching three times the power per liter from the NASCAR behemoth. This is made possible by being a twin-turbo hybrid power unit, or in other words replacement for displacement.

Formula 1 has an even more modest engine, on paper. F1 power units are a humble 1.6-liter V6. For those not feeling like doing the math, the NASCAR engine is 3.66 times larger. If there's truly no replacement for displacement, this would get obliterated by the raw American V8 muscle. However, that tiny V6 can crank out a thousand horsepower. That's around 625 horsepower per liter. Compare that against the 114 horsepower per liter from the NASCAR engine. That little F1 power unit is able to do this by being a product of the 21st century rather than from 1957. Like the IndyCar, it's a turbo hybrid, although with a single turbo instead of IndyCar's twin turbo.

Aerodynamics as a Substitute for Power

Far be it from me to downplay the importance of Enzo Ferrari, but did he know what he was talking about when he suggested aero is for people that can't build engines? In fairness to Enzo, we should give this statement some context. This quote goes back to 1960, up to which point race cars were built around a very different design philosophy from what followed in subsequent decades. Once upon a time, the idea was to make a land torpedo. Air was in the way and you wanted a torpedo to punch right through it, and a big engine to thrust it forward. Early F1 cars reflect this perfectly, as that's basically what they looked like. Put skinny tires on a torpedo, cut out a place for a driver to sit, and plop a huge engine in there to power it, and that was basically a classic Formula 1 car.

However, in time people came to figure out that air didn't have to be an obstacle in the way but rather something we could put to use. Tires also got wider to aid the cars in gripping around turns, as opposed to sliding through them. Wings started showing up on F1 cars, enabling them to corner faster than would have been possible without the aerodynamic components. Had Enzo been alive today, I can't imagine him seeing what we're capable of and still insisting aerodynamics don't have any place in racing. We will touch on this a bit more shortly, but first let's look at top speeds.

Fastest Speed Versus Fastest Laps

A misconception is that a car with a higher top speed is faster. Well, it's faster on a five-mile-long straight, but we don't race on long, straight expanses of highway. We race on race tracks, and even oval superspeedways aren't the same as neverending straights. If we look at the top speeds attainable by these classes, we'll see IndyCar leading the way with speeds up to around 242 miles per hour. Formula 1 can hit 235, though usually they're topping out lower than that. On a superspeedway, NASCAR can see speeds of roughly 200. If they were unrestricted, they could do 220 or better. On the Mulsanne Straight, WEC hypercars can do 215. GT3 can see speeds of 185 at Monza or Mount Panorama.

If you presume that the car with the fastest top speed would be the fastest around a track, you'd be mistaken. While IndyCar can reach higher top speeds than Formula 1, IndyCar is only third fastest among these particular classes around Circuit of the Americas, which we're using as our comparative benchmark since these classes have all ran laps of this same circuit. F1 is on paper second-fastest in terms of potential top speed, though they rarely race configured to hit such speeds, but they lap CotA significantly faster than anything else can even hope to. F1 has done 1:36.169 around CotA, which is 11 seconds faster than WEC LMP1 at 1:47.052. IndyCar, while boasting the fastest top speeds, trails behind in third at a relatively pedestrian 1:48.895, almost 13 seconds a lap slower than F1. WEC hypercars can lap CotA at 1:52.564. GT3 is looking at CotA times along the lines of 2:03.650, while NASCAR trails at 2:12.710.

While NASCAR engines boast almost three times the displacement of F1 power units, they lap Circuit of the Americas over half a minute a lap slower. If there was a race featuring both Formula 1 cars and NASCAR cars, every third lap F1 did would put NASCAR another lap down, as they would cover three laps for every two laps run by NASCAR. F1 top speeds aren't 50% higher than those of NASCAR, but they can lap CotA roughly 50% faster.

Expectation Versus Reality

Top speeds are largely just a nice-looking number on a sheet of paper. It doesn't matter much if a car is technically capable of doing it if it never gets to actually reach that speed. On paper, IndyCar can do 242 MPH, and under the right circumstances they can, but not at Circuit of the Americas. The fastest they can reach at CotA is about 190. That's over 50 MPH slower than what they can technically do. Formula 1 actually does hit 214 along the long back straight at CotA. NASCAR can do 200, or even 220 if unrestricted, but only hits about 170 at CotA. WEC hypercars reach 189, and GT3 can see 160.

It's even worse for road-legal cars. You can drop several-million dollars on a Bugatti and brag to me and anyone that will listen about your 260+ top speed, and how that's faster than even IndyCar. Good luck finding a race track, or really anywhere at all, where you can actually reach your top speed, though. Yes, your car is capable, but that's useless if you can't find anywhere to actually approach that sort of speed. Your Bugatti can't even get close at Talladega or Daytona, because they're not fifty miles of flat, straight highway. The Nürburgring Nordschleife is world-famous amongst car enthusiasts as the definitive proving ground, and supercars like the Bugatti Veyron or Chiron or the Mercedes-AMG One typically max out at around 190 to 200 and about 210 respectively. These speeds are several-dozens of MPH slower than what these cars can officially do, because they're limited by reality.

What all this means is that top speeds are cool stats but somewhat useless when determining what would be fastest in an actual race around a track.

Power of Aero

So what does aerodynamics bring to the table? Well, as we've demonstrated, a great deal. If you have a car that can do 210 MPH, why don't you do 210 through tight, twisting turns? Common sense tells us that it's because your car wouldn't be able to grip the road and you'd go flying off into a field, a wall, or a gravel trap. You have to slow down or you're going to have a bad time. If you're slowing down to navigate a turn, all the power in the world won't make you corner faster.

What will make you faster is aero. Lighter weight and grippier tires also help, but at the moment we're looking at aerodynamics. I've argued with people that only ever watched races without ever trying it; not even virtually. They've argued that downforce, like in Formula 1, is to make the cars easier to drive. Well, if you go for a Sunday drive at a pedestrian speed, yes, downforce should make it nice and planted and very comfortable. If you're comfortable, however, you're not racing. F1 drivers don't cruise around at a comfortable pace, but rather push the cars near their limits, and even with all the aero in the world they still have limits that can be exceeded with disastrous results.

Downforce isn't there to make the car easier and more comfortable. It's to make it more capable. It's the difference between being able to take a corner at 55 MPH and taking it at 80 MPH. Only part of a lap is high-speed straights and approaching top speeds. Much of the lap is weaving through slower turns, braking for those turns, and accelerating out of those turns. These are instances in which all the power in the world is useless, but where aerodynamics is incredibly valuable. Power will buy you speed on the straights, while downforce will buy you performance around the rest of the track.

Proof in the Pudding

We were huge fans of Top Gear, and the Top Gear Test Track served as an excellent test of car performance. It saw many dozens of cars lap it and this allowed us to directly compare actual lap performance of a wide range of cars. I remember when the presenters expected the powerful Bugatti Veyron to dominate the board, on account of its 8-liter W16 quad-turbo and over a thousand horsepower producing top speeds of 253 miles per hour. All that awesome might not only failed to drive it to the top, but it ultimately ended up 29th on the Power Board, even after excluding several vehicles. With a lap time of 1:18.3, it was beaten by more than a couple dozen cars, usually with less power and lower top speeds.

The fastest "qualifying" car (cars like the Renault R24 Formula 1 car are excluded) was the Ferrari SF90 Stradale, with a time of 1:11.3. That's seven seconds faster than the Veyron 16.4. The SF90 Stradale had literally half of the engine of the Veyron, with just a 4-liter V8 versus the 8-liter W16 of the Veyron. The SF90 Stradale produced 769 horsepower, which is substantially less than the Veyron's 1,183. The SF40 offered a top speed of a mere 211, which is far slower than the Veyron's 253.

The next fastest car was the Ferrari 488 Pista, making do with a measly 710 horses, and topping out at 211 MPH. Third is the Dallara Stradale and its whopping 395 horsepower. To highlight the disparity, the third-fastest qualifying car around the test track had a third of the power of the car that was 29th-fastest. We could play this game with the next 25 cars before we reach the mighty Veyron and its stunning 8-liter W16 quad-turbo 1,183 horsepower 253 MPH brutality against which dozens of cars ahead of it shouldn't have stood a chance.

In Summary

In short, the car with the biggest engine, most power, or highest top speed may be "fastest" on paper but not in around a track. On a Facebook group for The Crew: Motorfest players I was once discussing this with knuckle-dragging Neanderthals that couldn't wrap their heads around this. They thought I was somehow the one lacking basic comprehension skills. They even argued that faster lap times don't equate to winning. Well, if my F1 car is getting me around the track in 1:36 while your Indy car is plodding along at 1:49 per lap, I'd say that gives me a much stronger chance at winning.