Two Big Reasons Why Lower Horsepower is Safer for Teen Drivers

High horsepower and teenage drivers don't mix well.
High horsepower and teenage drivers don’t mix well.

It’s tough shopping for a car for your teenage drivers. You want them to be safe, of course, but you also don’t want to spend a fortune, especially since college costs are just around the corner (or are already part of your monthly expenses). I’ve written guides for safe and affordable vehicles for young drivers in the past, and there are simply more issues to consider than when buying vehicles for safer drivers with larger budgets. Even organizations like the IIHS don’t necessarily steer parents in the right directions.

It’s easy to overlook details, as a result, when trying to make the right decisions. Airbags? Of course! ESC? Definitely! Good crash scores? Yes! But there’s a bit more to the picture when it comes to choosing a safe vehicle for your teen driver. One of the most significant areas parents tend to overlook, in my experience, is the horsepower of the vehicles they’re considering for their children. And this can be a rather big area to overlook. Let’s dive into why.
Why is it important to consider horsepower when looking at cars for teen drivers? Aren’t safety features more important?
It’s absolutely true that safety features like crash scores, airbags (front and side), and ESC should be your first priorities when looking for vehicles for teen drivers; these features should also be your priorities when looking for personal or family vehicles at any stage of life. However, horsepower is also particularly important when choosing vehicles for teen drivers because it’s rather significantly linked to the way your teens are likely to drive once alone behind the wheel. To put it simply, vehicles with higher horsepower tend to encourage more dangerous styles of driving, while vehicles with lower horsepower tend to encourage safer driving, either directly or by not encoruaging more dangerous driving. Let’s look at two specific ways lower horsepower can do your teen drivers a favor.
1. Teens are less likely to speed in vehicles with less horsepower
 Speeding is implicated in roughly one out of every three fatal crashes, per the NHTSA, although the actual figures are likely much higher, given the near universal prevalence of speeding in our society. However, given that teenagers are more likely to be involved in fatal crashes per mile traveled than any other group of drivers until age 80, and that male teenage drivers are more than 4x as likely to be involved in fatal crashes than male drivers between 30 and 70 (and almost 6x as likely as female drivers between 30 and 70), it’s in our best interest as parents to do whatever we can to reduce the risks of our teenage drivers making bad decisions. This is particularly the case if we’re parents of male teenage drivers, who are statistically the most dangerous drivers on the road.
High horsepower is seductive to teenage drivers for the same reasons it seduces older drivers; it’s exciting and makes driving seem more fun, more exciting, more like a video game. Our culture glorifies speed and adrenaline and excitement; we equivocate the ability to drive quickly with the ability to free ourselves from the worries of society, blaze new paths, and experience all manner of adventure. It’s a big part of why muscle cars are popular among middle-aged and senior adults; speed symbolizes vitality and youth and vigor and power. Unfortunately, these false associations also attract teenagers, who have less life experience than older adults and are less likely to be able to restrain themselves from chasing the thrills that come with speeding.
Vehicles with less horsepower, on the other hand, simply aren’t exciting. Yes, it’s possible to break the speed limit in any vehicle, but we’re much less likely to do it, or at least do it grievously, in vehicles that aren’t designed to do so easily and with impunity.
2. They’re also less likely to engage in risky driving (like aggressive lane-changing, racing with friends or strangers,  and red-light running)

The second and more broad reason to avoid vehicles with high horsepower for ones with low horsepower is that vehicles with less horsepower are less likely to encourage teenagers to engage in a wide range of risky behaviors, including aggressive lane changes, street-racing (whether with friends or with strangers), and running red lights.

The reasons behind this are related to the reasons behind why teens (and all drivers) are more likely to speed when behind the wheels of more powerful vehicles and more likely to drive prudently when piloting normally powered vehicles: the power is seductive. Many studies have shown people are more likely to display aggressive behaviors when driving or commuting than when walking or cycling, and statistically speaking, we’re more likely to act as if we’re characters in action movies (changing lanes rapidly, revving our engines at stop lights, trying to beat stale yellows) when we think we’ve got the muscle beneath the hood to do so. If this doesn’t sound like something you’d do, that’s great! But if you’ve got a teenage driver–and a male one in particular–he or she is unlikely to have as much temperance as you do, and it’s highly likely that you didn’t have as much restraint as you currently do when you were 16, 17, 18, or 19.

Cars with less power are driven more practically and less aggressively, which makes them and their drivers safer.

But I heard higher horsepower was safer, since it allows you to merge safely / avoid errant vehicles / etc…?

This is a frequently-given reason for choosing vehicles with a bit of “get up and go!” as a good friend of mine calls it. However, the truth is that virtually any vehicle made since 2000 onward has more than enough power to merge safely, and you don’t need 250 horsepower to make it into a lane or to avoid a vehicle that has swerved into yours. What you are more likely to do with that extra horsepower is speed or drive recklessly, which is more likely to lead to a collision or a loss of control. Don’t believe the hype; pretty much anything that comes with an EPA sticker has enough power to get you where you need to go or keep up with traffic. If you’re wanting more power just so you can”have it when you need it”, keep in mind that your teenager isn’t going to be nearly as good of a judge of “when s/he needs it” as you are.

What do you recommend as a horsepower limit for vehicles teenagers are likely to drive?

That’s a great question. I hesitate to give a specific number, as different vehicles react differently with different amounts of weight and engine capacities. However, more broadly, I’d recommend choosing the smallest cylinder option available within a given vehicle, and the lowest horsepower trim level available if you have the choice. Again, whatever you choose will have more than enough power to help you travel wherever you’re going safely. The smaller engines and lower horsepower trims, as an aside, will almost always result in better fuel economy too, as the engines won’t be excessively large. And if you’re considering two otherwise similar vehicles, be sure to take a look at the horsepower figures; what you find may surprise you, and may make a large difference in how safe of a driver your teen is when s/he gets the keys.

If pressed for a number, I’d recommend trying to keep the horsepower to 200 or lower, or at least as low as possible past 200 if you can’t get below 200. In my most recent comparison of safe vehicles for teen drivers, for example, that would mean choosing the Galant or Jetta over the Passat or TL; it would mean choosing the CR-V over the Outlander, and the Yaris over the Forte.

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How To Survive a Head-On Collision – Slow Down (to below 43mph)!

To survive a head-on collision, your odds are best below 43 mph.

Lately, I’ve been writing a lot about Vision Zero. It’s an initiative a number of wealthy countries around the world are following to different degrees with the overall goal of reducing auto fatalities in their populations. One of the central tenets of Vision Zero is the belief that roadways need to be designed to protect different kinds of travelers from coming into contact with each other above particular speeds. For example, if you’re an unprotected traveler, like a pedestrian, any roadways you use that might put you in contact with cars (e.g., cross-walks) should not have traffic traveling any faster than 20 mph. These guidelines also exist for individuals traveling in cars who might come into contact with other cars, which is precisely what this article is about.

What can we do to increase our odds of surviving a head-on collision?
To put it simply, if you want to survive a head-on collision, the best way to do so is to avoid getting into one to begin with. But if that’s not possible, the second best way to survive is to drive as slowly as possible prior to the collision–ideally, no higher than 43 mph. More broadly, since collisions are difficult to predict but the roadways we choose are far more likely to be under our control, I’d avoid driving on any undivided roadway with a posted speed limit above 40 mph.
What makes 43 mph the limit for survivability?
The specific figure comes from research related to Vision Zero, such as a Monash University study in 1999. The researchers came up with a series of guidelines related to the highest amounts of violence, or crash forces, the human body could tolerate under certain assumptions (e.g., well-designed vehicles with crash structures, or passengers wearing seat belts) without risks of serious or fatal injuries. For vehicle occupants traveling on roads where frontal impacts were a possibility between cars, they recommended a long term speed limit no higher than 70 kph, or approximately 43 mph.
But I know  / heard of someone who survived a head on at 50/60/80 mph!
While it’s certainly possible to survive frontal crashes at higher speeds, the odds of doing so drop exponentially above this speed. After analyzing dozens of crashes over the last several years, I’ve found survivors of head-on collisions in a range of speeds, but the rate of fatalities has always risen dramatically with the speeds of the collisions, while the rate of survival has always dropped as quickly. Remember that a crash with a 50% survival rate suggests that if you and someone you love are sitting in the front row of a vehicle, statistically speaking, either you or your loved one isn’t going to survive such a collision. Those aren’t the kinds of odds you want on your side each time you drive.
How do other safety organizations (i.e., the IIHS) feel about this figure?
While the IIHS doesn’t specifically advocate 43 mph speed limits, they have repeatedly advocated slower speed limits and bemoaned the rising tide of speed limits throughout the country. Additionally, one of the most direct endorsements of a 43 mph limit for head-on collision survivability comes from the IIHS’ frontal moderate- and small-overlap crash tests. Both of these tests are conducted at 40 mph, and are designed to simulate the effects of a vehicle crashing into a vehicle of equal mass traveling in the opposite direction at 40 mph. They’ve noted that these kinds of crashes are already considered to be “severe” ones, and that tests are not conducted at higher speeds due to the impracticality of designing vehicles capable of protecting occupants at higher speeds.
Does this mean my car / SUV / minivan / pickup is only designed to protect my family at up to 40 mph?
In a head-on collision, yes. This isn’t because car manufacturers don’t care much about keeping people safe at high speeds or that organizations like the NHTSA and IIHS don’t care about things that happen at higher speeds; again, it’s simply a reflection of how much additional energy vehicles carry at higher speeds, and how difficult it is to design vehicles to protect individuals above those speeds because of how energy increases with speed. But once again, when you hear that your vehicle comes with a 5-star frontal crash rating or a “good” frontal impact score (whether head-on, moderately overlapping, or small overlapping), it’s essential to remember that this only applies for crashes at 40 mph, and with vehicles that weigh as much as or less than your vehicle. At higher speeds, there are no guarantees.
How much more severe is a crash at 70 mph than one at 40 mph?

It’s important to remember that the forces in a collision quadruple when speeds are doubled, rather than simply doubling, because kinetic energy increases with the square of velocity. To put this in practical terms, a crash at 80 mph carries 4x the energy as a crash at 40 mph, even though the speed is only 2x as fast. As noted above, your vehicle is only designed to protect you from a crash with an equal or lighter mass vehicle at 40 mph. Let’s use that as a baseline, where your vehicle handles 100% of tested forces while allowing you to survive the crash with minimal injury. At these speeds, your odds of survival in a vehicle with a “good” frontal score are close to (not quite, but close to) 100%.

A 70 mph crash carries more than 2x as energy, or precisely 306% as much energy as the 40 mph crash (100% of tested forces). In my observations from studying crashes, once you get up to around 300% of the forces your vehicle was designed to handle, your odds of survival drop down to around 25%. To put it another way, in a head-on crash at 70 mph involving 2 vehicles with 4 people in the front seats, only 1 of the 4 people involved is likely to survive.

This is the risk we run every time we drive at 70 mph in an environment with a possibility of head-on collisions (i.e., every undivided highway in the country).

If crashes are this much more dangerous above 40 or 43 mph, then why do we have speed limits at 55, 65, or 75 mph?

That’s a great question. A basic answer is because our society (as well as virtually every other around the world) prioritizes speed over safety when it comes to auto travel. Additionally, most people aren’t aware of the dramatically increased risks that come from higher speed limits until it’s too late (you can’t advocate from beyond the grave). However, it’s important to remember, too, that speed limits beyond 43 mph can be tolerated with low risks of severe injury or death as long as the risks of head-on collisions are eliminated, which is possible through good road design. The challenge is to bring that good road design to a country that’s plagued with poor road design.

What do you mean by poor road design?

Poor road design, per Vision Zero, in this context refers to roadways with an opportunity for head-on collisions that permit or encourage vehicles to travel beyond 43 mph. In other words, two-lane undivided highways with 50, 55, or 60 mph (or higher!) speed limits are roadways that shouldn’t exist, but do throughout the US (and globe).

What does this mean for my family and I? Do we have to drive at 43 mph everywhere?

Not necessarily. But as noted earlier, I’d certainly try to avoid driving on any undivided roadway with a posted speed limit above 40 mph. The risk increases exponentially with the speed of traffic. And given the propensity of people to speed in this country, a road with a 40 mph PSL will most likely already be dealing with 45-50 mph traffic. You can do the math for higher speeds.

If you’re about to get into a crash, the best thing you can do in the three seconds beforehand are to slow down as much as you possibly can. If you have the luxury of choosing your roadway, stay away from undivided roads with speed limits above 40 mph. Your life could literally depend on it.

If you find the information on car safety, recommended car seats, and car seat reviews on this car seat blog helpful, you can bookmark and shop through this Amazon link. Canadians can bookmark and shop through this link.

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