Speeding is a waste of time & money

Speeding is a huge waste of time and money. Reckless driving in general is decidedly bad for people on the path to financial independence. Not only does it save very little time (if any), but it can be very expensive to you in the long run. We are all here to save money not waste it, right? Call me old but I’ve gladly shifted myself to the center lane on cruise control. Feel free to comment in support or to tell me how wrong I am.

Why people speed

I assume people continue to speed everywhere in their cars because they honestly believe they get to their destinations much faster. I have to believe that otherwise all that reckless driving is just speeding for no good reason. I get it. At face value it makes sense to think speeding gets you there faster. Travel time is a function of distance and rate of travel so increasing speed would reduce the time end of the equation.

The problem is most people are never going to sit down and do the math on exactly how much time it actually saves. Thankfully for you I did. This topic gets me on a deep level because I simultaneously get to do a lot of math while ranting about one of my pet peeves. It’s perfect for me. 

First, some background

I’m not new to this game. I too did some reckless driving in my youth. We probably all did to one degree or another. We lived in a world free of many responsibilities, carried a dangerous assumption that we were invulnerable, and thought we knew everything. I’m pretty sure I spent the first 5 years of my driving life always 5 to 10 mph over the speed limit. I assumed that was just normal. Based on what I see out on the roads today it may not have been a bad assumption.

I feel super old saying this but as each year passed my speedometer inched closer and closer to the speed limit. Now that my car has super fancy things like cruise control I can set it and forget it at that level. My first car didn’t even have carpet on the floorboards so cruise control was definitely not included. I guess I just started realizing the trade-off for speeding everywhere wasn’t worth it. I’ll try to make that argument to you too.

We need to define this problem

Clearly I’ve done the math on this. I know that on a 300 mile road trip where you average 15mph over the speed limit the entire way you will save some time. I’m not disputing gains on a cross country trip like that. I will dispute using that as a basis for your argument. People don’t regularly drive that far. According to AAA the average driver does around 2 trips a day totaling 31 miles which would be 15 mile trips.

You’d have to go pretty far over the speed limit (and sustain that speed) to make any real gains on such a short trip. This is assuming you are traveling in a straight line with no stops, traffic, or other slowdowns. You can see where the prospects are getting dicey for the reckless driving fans already here.

Show us the math, you coward

Slow down… we all love math. I think we need to start with the basic travel time calculation before we go into why it is garbage. Just kidding, mostly. Travel time for any trip is equal to the distance divided by the speed. It really isn’t more complicated than that and many people stop their calculations there. Here is a table showing the travel time for common distances and a couple levels of speeding to see how it pans out.

Travel Time Using Basic Formula

What about traffic and stop lights?

Exactly. All of the calculations above assume you can maintain the stated speed the entire trip and never have to stop for any reason. Has that ever happened to you? Of course not. Nobody can instantly hit 45 mph in their car and keep it going without encountering traffic, a stop sign, a stop light, or any number of things that can slow you down along the way. Unless you are a fire truck with the sirens on or a helicopter pilot.

Each one of those slow down events not only means you lose time waiting but reduce your overall average traveling speed. You need to gradually slow down at traffic stops and gradually speed up when clearing them. That means it is very unlikely that a driver actually achieves the speeds used in the table above.

We don’t live in a 2-D world

These calculations might work for 16-bit Mario because he traveled in a straight line with almost no turns. Unfortunately at least for me, I have to make at least 4 to 8 turns to go nearly anywhere. Each segment of the trip means a slow down and ramp up of your speed to make the change in direction. It is inevitable that some of those segments prevent you from hitting your desired speed due to length or speed limits. 

Just another reason why those basic calculations don’t pan out in the real world. The 5 minutes you gain by speeding could easily be crushed by a stop sign, some slow traffic, a school bus, or almost anything else. The gains are so small that almost any of the wild card variables are enough to cancel them out.

Cool. Show me the results already

Being the huge data nerd that I am (who taught himself to code), I wanted to make the calculations for travel time a little more robust. The numbers I generated needed to be calculated for a base case (no speeding) as well as 5 and 10 mph over the speed limit which seemed like common amounts. The slowdown events (stops and traffic) should be included with a random wait time. I also wanted to incorporate some randomness into the math.

The simulation code essentially chops the input distance into a set number of segments of random length and calculates the travel time for those pieces. It then adds in the random wait time between segments and adds in a small random amount of time for traffic depending on the total distance traveled. 

This one is just for me #Justice

To be fair, the simulation adds on 30 minutes of wait time for speeders to get a traffic citation. There is a 1 in 2000 chance of getting pulled over if you are speeding on average in America and the code should reflect that.

Lastly, the simulation sends the driver on 24,000 of these randomized trips to determine the average travel time. This Monte Carlo style simulation allows for all of the randomness needed in the experiment while accounting for their rarity. The Law of Large Numbers means we should get close to the “real” average in the end this way. Lets see if reckless driving pays off together.

The Results

Travel Time Using Python Simulation

Are these results surprising to you? They surprised me the first time I did this math many years ago. On the 15 mile trip you are saving 2 – 4 minutes of travel time by speeding (with +/- 2.5 minutes standard deviation too). That isn’t worth the hassle of speeding. On a 30 mile trip you are saving only 4 – 7 minutes by speeding (with +/- 2.5 minutes standard deviation).

Is saving 7 minutes worth it? Just leave a few minutes earlier. Seven minutes is 0.7% of the waking hours in a day… not even an entire 1 %. Even on longer trips I personally don’t see the payoff of going too far over the speed limit. On the 60 mile trip speeding 10 mph over the limit gets there 14 minutes earlier. You might wave 30 minutes on a 120 mile trip at that rate but that is still not a huge improvement on a 3-4 hour drive.

Fellow data nerds: histogram plots

These plots show all 24,000 trips per speed on a chart to show the frequency of each result. The taller the bar the more likely that travel time is occurring in the result set. It is an excellent way to visually see the distribution of travel times for each input.

It is also a great way to see just how much the results of the speeding drive times overlap with the non-speeding time. Take the 15 mile trip chart below, the average trip taken daily by an American driver. The table above notes that on average speeding 10 mph over the limit gets you there 3.5 minutes faster. However, the plot shows that almost 25% of the results overlap meaning the times would be the same.

What if I change lanes a lot though?

Stop it Toretto. Seriously, nobody likes that driver. You can see above that the speed you travel isn’t really getting you there much faster. Changing lanes constantly probably won’t either, especially on urban roads. All it does is give you the illusion of agency in the matter. It feels like it helps because you are making the choices and feel in control when in reality changing lanes constantly has negligible results.

Throwing time out the window, changing lanes constantly significantly increases your chances of getting into an accident. You could be the greatest street racer in the world but the dozens of cars next to you are definitely not. Reckless driving in this manner only makes it more likely another driver doesn’t see you or anticipate your change.

Mental Fatigue

Even if you can somehow get some marginal gains by speeding and changing lanes far too often, there are other considerations. That style of reckless driving is stressful. Constantly monitoring your speed and looking for openings in traffic to shift lanes will wear you down. You are needlessly adding to the number of decisions you have to make each day.

Decision fatigue is a real thing. You may not realize it but reckless driving (even minor ones like slightly speeding) can be mentally draining. This all assumes you aren’t already drained from life itself (I see you over there… the entire year of 2020). Why not join me in the middle lane on cruise control where life is far less complicated.

Immediate costs of reckless driving

The personal finance community will easily be able to identify the immediate costs related to reckless driving I imagine. More frequent and aggressive starts and stops increases the wear and tear on your vehicle and can cause undue maintenance. Higher speeds for shorter time periods (not highway driving) results in poor gas mileage which hits your wallet at the gas station. Traffic tickets are an obvious unnecessary expense nobody wants.

Speeding tickets in Florida vary from $129 for low level offenses and over $200 for higher speeds. Assuming you have no court fees or lawyer expenses, even this or a reckless driving infraction can seriously bust your insurance budget. Per some sources it can raise your annual car insurance premiums by up to $900 since you are now a high-risk driver.

Long term costs of reckless driving

The immediate costs are easy to spot. It can be harder to see the long term implications of our choices when the stakes are low. As fans of the financial independence movement you’ll understand how compounding gains on investments really add up over enough time. Paying a traffic ticket today or higher car insurance for a few years may not seem that consequential now. But what if you were able to stick those funds in your retirement (or other investment) account instead? That $200 ticket and extra $900 a year would really add up over the next 25 years to some serious pocket change.

Not to be morbid, but there could be physical tolls as well. One minor car accident could forever alter your life even if everyone survives. Lost mobility could seriously reduce your income making potential and participation in activities you love.

TL;DR  – Conclusion

Besides the obvious danger of reckless driving, it just isn’t worth it to speed everywhere. You are unlikely to get to your destination measurably faster on any trip that isn’t cross-country. Not only are you not getting there much faster but you are significantly increasing your chance of being in a car accident or getting a traffic ticket. As a bonus to all of that you end up stressing yourself out with needless decisions on the road.

Save your money and sanity. Join me comfortably in the center lane on cruise control. Sure, we might get there 4 minutes later but those of us pursuing financial independence have all the time in the world. We also have all of those savings from great gas mileage, lower car maintenance, and cheap car insurance invested in the stock market.

I’m not saying that if you stop speeding all of the time you’ll retire earlier. I’m saying that it wouldn’t hurt. The aggregation of marginal gains strikes again. 🙂

Want more info on the code?

I wrote this simulation in python and would be glad to discuss it with anyone and share the code if interested. Writing this type of simulation out in code is a great exercise in more fully understanding the underlying calculations. It’d be hard to plan out the steps to add up the travel time and add in the random circumstances without thinking it through. I personally enjoy the trial-and-error of getting it all right.