For some people, a sports car is just a convertible that is appealing and looks nice from outside. For others, sports car is a two-seater car with nice leather interior. And for some people, it is a vehicle made at a "certain point in time'. They might say that such and such car model was like a sports car in 1970s but not now since it looks very different.

The purpose of this article is not to debate who is correct and who is not, but to examine certain parameters or characteristics that make a car "sports car".

First of all, if you would have noticed, cars come in different shapes and sizes. There are coupes, sedans, hatchbacks and even "four door coupes". For a manufacturer, all these shapes and sizes are result of market demand and to increase market share. For example, BMW now makes sport utility vehicles(SUVs) and Porsche is planning four door sedans to satisfy a certain market segment.

For the sake of simplicity, we are going to exclude SUVs and trucks from the scope of this article. Most people know what kind of performance numbers a Jeep SRT8 can produce but when Chrysler decided to produce that vehicle, their intentions weren't to create a track vehicle but to produce a vehicle that people can show-off on city streets with huge horsepower and still have a SUV for their daily needs. So to keep this discussion focused, let's forget about the AMZ minivans and SRT8 trucks and SUVs.

Let's review certain features that are unique to a specific class of vehicles and then decide if that class of vehicles is what average person know by a name "sports car".

1. Gross Weight - Everything that physically exists on earth has a mass and thus associated weight with it. Cars are obviously no exceptions. However, their weights can vary on a large scale. On one side of the scale, you could find a car under 2000 lbs and on other side you could easily find one with over 5000 lbs.

Is weight one of the parameter that a sport car is going to be judged on? Simple answer is "yes". Let's consider another analogy to understand the importance of weight in a car's performance. If you have an elephant and a horse and both can do 30 mph, which one would you rather ride? As far as speed goes, ride on an elephant doesn't seem much different than a horse. Now let's add another variable to it. If you're going in a straight line, may be it doesn't matter. But what about a road with curves and turns? Now you start to think. At 30 mph, do you think that negotiating a sharp turn is going to be same whether it's an elephant or a horse? Of course not. You probably would not make the turn on an elephant due to sheer inertia and momentum. Mass transfer or momentum transfer is a concept in physics and it would work exactly the same whether you're riding an elephant or a car. Weight is your biggest enemy when making sudden direction changes at higher speeds. Weight is so important that car manufacturers are continuously looking for lighter materials to replace steel and aluminum. Current technology is carbon fiber. This material is lighter than steel but at the same time, it is 10 times stronger. So why don't we use it in cars? Well, first of all, it is very expensive and it is difficult to work with. You can't bend it like steel and when it breaks, it breaks in hundreds or even thousands of small pieces. Even with those issues, car manufacturers have started to use it in high-end performance cars(We'll not call anything a "sports car" yet) because of the weight advantage. BMW uses carbon fiber for roof in its M6 coupe as well as E92 M3. Porsche Carerra GT is entirely made of Carbon fiber. Ferrari has used it in Enzo. So you see the trend. These are all very expensive automobiles with a narrow audience that can afford to pay for the cost.

Another cheaper solution is composite fiberglass. Fiberglass is the material that most car manufacturers use for bumpers. It is nowhere close to steel or aluminum is strength but it is light. One of the best implementation of Fiberglass body is Lotus Elise. Elise is a small car with just 192hp and 138 ft-lbs of torque. Those numbers are not impressive by any standard. But let's look at what fiberglass has done to the car's performance. Elise weighs less than 1900 lbs. How about some performance numbers? 1900 lbs car with 192 hp engine does 0-60 in 4.7 seconds and quarter mile in 12.9 seconds. Lotus Elise is even more impressive on track; it can run circles around much more powerful and bigger cars and put them to shame.

So now you started to understand the importance of lower weight. Since most cars aren't made on carbon fiber or fiberglass, Let's consider the optimal weight for cars made of steel or aluminum. Based on decades of testing and track experience, most experts agree that a car with weight range of 3000 lbs - 3700 lbs can still do wonderful things and stay nimble if it meets some other parameters.


2. Horsepowe/Engine Size- Whether you're on a dirt road, track or anywhere else in the world, there is no substitute for horsepower. You can make a car as light as you want, but if you don't have horsepower, you aren't going anywhere fast. So horsepower is an important piece of this puzzle. However, you could have impressive performance numbers even with a low horsepower car if you have your other parameters right. Lotus Elise is only 192 hp, Honda S2000 only has 240hp. These are not big numbers but both of these cars are amazing vehicles due to some other factors that we'll discuss here. American car manufacturers have used the technique of bigger engine size to produce big horsepower numbers while European and Japanese have relied on smaller engines with higher rev limits to achieve higher horsepower numbers. Dodge has an 8.4L (Liter) engine that produces over 510 hp in its viper while Ferrari has a 4.3L engine that produces 490hp at 8500 rpm in its F430 coupe. BMW M GMBH has produced a V10 engine for it's M5 and M6 cars that produces 500hp. New upcoming BMW M3 will have a 4.0L V8 that is rated over 420hp at 8400 rpm.
But what is the bottom line here? If you have noticed, most of these refined engines have achieved at least 100hp/L and that's the current benchmark of a highly tuned engine. So if you find a car with over 100hp/L, you're looking at something special.

3. Red Line/Rev band/Torque - Are these related? Probably not. But as you read more, you will understand why they are listed together. Remember horsepower discussion we just had? What needs to happen for an engine to produce 100hp/L?
If you examine the specs of these engines, you will find a common thread. All of these engines are "Rev happy" or high RPM engines. Ferrari engine has its red line over 8500 rpm. Current BMW M3 engine(3.2L 333hp) is rated at 8000 rpm. Remember Honda S2000? That car has just @ Liter, 240hp engine but with amazing performance numbers. Reason - it can rev up to 9000 rpm, astonishing figure for a streetcar. Let's expand a little on this. If you have ever watched a Formula one(F1) race, you would have noticed that scream coming from the engines. Formula one racing technology is the epitome of racing technology in existence. Current F1 cars have a 2.4L V8 but have engines that can rev up to over 19,000 rpm and that's why they produce over 1000hp and faster acceleration that any other road machine can.
Now you started to understand the relationship among acceleration, torque and RPM limit. Most of these vehicles have a low torque number but each vehicle accelerates longer in each gear and when they shift out of a gear at the red line, they are put right back on the top of torque curve in next gear. In simple terms, if you have two similar cars(weight, similar torque curve), the one that has a higher red line will always be faster. So in ideal world, you would like your car to produce not only a high torque but also at the higher rpms.

4. Gear Ratios/Torque Curve - Here is another one. Gear ratios? What does that mean and how can it make a car fast? Gear ratios are simply the ratios of the rpm at which your engine is rotating to the rpm at which your wheels are rotating. Final gear is usually 1:1 unless a vehicle has a different ratio for fuel economy reasons. Before we explore rpm and torque relationship, let's get one of the simple definitions out of the way. What is peak torque? Peak torque for any car is the torque value in its rpm band where a car will accelerate hardest in any given gear. So if your car has a peak torque at 4000 rpm, that's where it will push you back hardest in your seat.

BMW E36 M3 is a great example to understand the effect of gear ratios. U.S specs E36 M3s have 240hp and 236 lb ft at 3,800 rpm. It has a 5 speed transmission and here are the gGear ratios-

1st Gear - 4.20:1
2nd Gear - 2.49:1
3rd Gear - 1.66:1
4th Gear - 1.24:1
5th Gear - 1:00:1
Final Drive - 3.23:1

Based on these numbers, E36 M3 is doing around 3,800 rpm in third gear at around 60 mph. What does that mean? If you look closely, at most of the track events, you're probably going to run a speed range of 30 mph - 110 mph and in 3rd and 4th gear most of the times. What this clever gearing does to you is to keep you at the peak torque during most of the track driving and hence great performance. Another benefit is highway driving, 55- 65 mph is the legal speed limit in most of the United States and if you're in 4th gear you're sitting at 3000 rpm and if you need to pass someone, only thing you need to do is to downshift and all of a sudden, you're in a go cart since a downshift will put you right at the peak torque.

5. Suspension and Steering Response - Suspension is probably the least visible component but makes a huge difference. It is also true for steering response. A razor sharp steering response can make a car lot more fun to drive. Some cars even have variable steering, that actually adjust the response based on the vehicle speed. It make sense since one quarter turn of steering will result very different results at 20mph and 100 mph due to the fact that you've travel a lot more distance in the time it takes to make that steering turn at 100 mph. BMW cars are well known for their handling and steering response. If you want to get a better understanding of handling and steering, go test-drive a regular BMW 3 series. Most people will be impressed. But we are not done yet. If you want to see how a good handling car can be made a great handling car, test drive the M version. So try a BMW M3 right after you have driven a 3 series. What would you notice? First thing you would notice is the steering response. If a 3 series has a good steering response, an M version(M3) would show you what a razor sharp steering response is. If your 3 series handling was good, you would learn the meaning of great handling. Bottom line - even though you would not see many differences from outside(a 328Ci looks similar to an M3 to most people), under the skin, an M3 is a very different animal. So learn to appreciate a vehicle from outside and based on its appearance, but remember, there is lot more under the skin that can totally change your perception.

Based on these parameters, I think we have some benchmarks that you can use to evaluate if a car fits in a sports car category or not.

1. Weight and Horsepower - These can be combined in a single factor. Most experts agree that a ratio of 10lbs/hp is a good test. If a car has 3500 lbs and also has 350hp, this car has a ratio of 10 lbs/hp. Lotus Elise has 1900 lbs/192 hp = 9.89 lbs/hp. Lower the number better is the rating on this scale. Also remember to use weight rule with this rating for evaluation. For example, consider a 6000 lbs car with 600 hp and a 2000 lbs car with 200 hp. Both vehicles have a rating of 10 lbs/hp, but they will handle very differently.

2. Engine rating - Currently 100hp/L is a widely acceptable benchmark. Some manufacturers have deployed superchargers and turbochargers to boost hp but engine rating for them is not same as for a naturally aspirated engine. Engine compression ratio can also be used in conjunction with this number. Generally speaking, engines with a high compression rating(10:1) are highly tuned but it is not always true.

Beyond these factors, you can consider other figures such as 0-60 time, quarter mile time, trap speed and 60-0 stopping distance. You will be surprised to see that cars with good ratings on above benchmarks will usually come out on the top.

In our opinion, these are the important parameters to decide whether a car is considered sports car or not. Don't make your opinion based on the looks, there are plenty of two-seater cute convertibles out there, but are they real sports car? Absolutely not. They are the pretenders and you can separate the real ones from the pretenders in couple of minutes once you head over to a track. And don't worry about the number of doors or seats, A car is a sports car as long as it passes the test and retain the true spirit of a sports car.

Here are some great examples and real world data to back these facts up.

Ferrari F430
4.3L V8
HP - 490 hp@8500 rpm
Torque - 343 ft-lb@5250 rpm
Curb Weight - 3197 lbs

Ferrari F50
4.7L V12
HP - 513 hp@8500 rpm
Torque - 347 ft-lb@6500 rpm
Curb Weight - 2710 lbs

Lamborghini Gallardo
5.0L V10
HP - 500 hp@7800 rpm
Torque - 376 ft-lb@4500 rpm
Curb Weight - 3153 lbs

Porsche Carrera GT
5.7L V10
HP - 605 hp@8000 rpm
Torque - 437 ft-lb@5750 rpm
Curb Weight - 3043 lbs

BMW M3(E92)
4.0L V8
HP - 420 hp@8300 rpm
Torque - 295 ft-lb@3900 rpm
Curb Weight - 3648 lbs

We can go on and on to add more examples but you can definitely see a common link here.