How to improve lap times with a simple speed/distance graph

Find the Flats

In most cases, on most tracks, you should either be accelerating or decelerating at all times. Your minimum velocity for a particular corner should occur at or just before the apex, and aside from that, you’re either accelerating toward the next corner or decelerating toward the apex.

The first things you can quickly identify on any speed/distance chart are flat, horizontal areas indicating steady speed. Yes, some tracks have segments that read as relatively flat areas, but even the most constant of constant-radius corners typically has a fairly small section of vMin–short for minimum velocity–as you try to exploit the track geometry to extend your acceleration area out of the corner and delay your deceleration into the corner. 

Even the Nordschleife’s legendary banked Karussell, which goes well beyond 180° and has a constant radius, shows a vMin early in the corner as you roll in over the lip. After that, the speed climbs slightly through the corner as you feed throttle and the car presses increasingly harder into the banking.

Flats are huge red flags that need to be investigated. If those flats occur in a corner, ask yourself if you could alter your line to find a single point–or at least a shorter point–of vMin and effectively extend the pre- and post-apex straights. 

If that flat occurs on a straight, ask yourself why you’re lifting and going to a neutral throttle. Maybe you’re working up to speed on a new track, in which case some mental health lifts are certainly justified. Or maybe you’re just giving yourself more time to spot visual references for your next major control input. 

Flats on straights are telltale indications of a novice driver, and it’s totally okay to be a novice. But as a novice now armed with the ability to quickly spot areas that could use improvement, you’re now well equipped to raise your status.

Sharpen the Peaks

Once you’re satisfied that you can produce a reasonable explanation for all of the flats on your chart, it’s time to turn your attention to the stuff at the top, particularly the peaks that show the transition from acceleration to braking.

What did we say earlier? In a perfect world, you’re either accelerating or decelerating. If you aren’t producing some kind of force on the tires, then you’re just coasting–and coasting is the enemy of lap times. 

A good indicator of how well you’re maximizing your straights is the sharpness of the transitions from acceleration to braking when entering a corner. Ideally, you want the acceleration curve to terminate and then immediately drop with as little lag or delay in between the two as possible. The less lag you have, the sharper those peaks will look. Areas for improvement are typically going to manifest in one–or a combination–of three ways. 

Red flag: A flattening of the speed trace reflects an area where the car is essentially coasting and needs to be investigated. This one precedes a braking area, so it could be indicative of the driver lifting early and coasting toward the braking marker.

The first: the overly gentle entry. The acceleration curve will climb steadily and then taper and shallow out a bit, if not go completely flat, before braking initiates. 

The second: a steady climb of the acceleration curve to the point of braking but then a gradual drop in speed followed by a more dramatic drop indicative of an overly gentle brake application. 

The third: Combine the two, and you’ll have the rounded top showing that you’re both coasting into the braking zone and initially applying the brakes too gently. This third red flag is pretty indicative of what you’d see from someone learning a new track, so if that applies to you, it’s good to monitor how those round peaks sharpen from session to session or even lap to lap. This can be a good indication of how quickly you’re getting up to speed on the track.

There are a few real-world situations where these indicators aren’t necessarily a red flag–if you’re in a fuel-saving mode, for example, those lift-and-coast moments before braking will appear fairly frequently–but for most corners, a nice, sharp peak at the top of the curve should be your goal.

Mind the Dips

Like the peaks at the tops of the curves, sharp valleys are also your goal. Thanks to the complex nature of many corners, however, expect some variation here. 

For example, it’s not unusual to see a speed trace shallow out as it nears the vMin point of the curve. This is due to the reduced rate of deceleration during the trail braking phase, so the distance represented by that shallowing is going to vary based on the shape of the corner, your trail braking skill, and your car’s inherent balance when decelerating and adding corning load.

Likewise, the far side of the vMin point, once you’re accelerating through and past the apex, can show a slower building of speed. Like the corner-entry phase, the initial acceleration phase can be shallow as the car digs for traction while also trying to accelerate, then ramp up quickly as you fully unwind the wheel. 

Red flags: Transitions through vMax and vMin should be decisive. That’s the best way to spend the most time going fast and the least time going slow. A speed trace that peaks with a rounded shape is indicative of gradually rolling off the acceleration and gently rolling into the brakes. Likewise, one that bottoms with a rounded shape shows the brakes being rolled off gradually and the throttle being applied gently. There are corners where this is a necessary technique, but spotting these on your speed trace can warrant a deeper examination. Green flag: Typically your acceleration curve should end in a decisive braking application.

So don’t sweat those shallow areas too much, although you should strive to minimize them when possible. Still, there are a couple solid red flags to watch for here. The first possible issue is an extended area of vMin. Remember, even in the longest corners, your minimum velocity is still going to tend to occur in a very small area between deceleration and acceleration. If you’re seeing extended flatlining at vMin, investigate.

Also, be mindful of humps and spikes in this area. The deceleration rate shallowing, then dropping, then shallowing again toward the vMin point probably means you thought you hit the brakes too lightly and were going to overcook the entry, then either applied more braking or scrubbed too much speed on the entry, then had to hit the gas again before the apex. 

Likewise, a hump after vMin probably means you got on the throttle too early, had to back out, and then reapplied throttle as the car regained the grip that you took away from it.

Beware of Spikes

Finally, scan your speed/distance graph for any humps, spikes or dips–small areas where the curve detaches from the nice flow of the line and bumps up or down. In general, these curves should be fairly smooth from peak to valley and back again. 

Red flags: Spikes in the speed trace usually reflect driver error. During corner exit, a speed spike can show too-early acceleration that had to be given up for a course correction before track out. In the braking trace, a spike can indicate lockup, aggressive ABS intervention or simply misjudging the braking point and adjusting pedal pressure too aggressively. Strive for the green flag look of a steadily rising or dropping line into and out of corners.

These anomalies can be caused by momentary wheelspin, unexpected brake lock or a sideways moment in a corner, but generally they’re easy to explain because there’s usually some drama involved. And stuff that’s easy to explain is typically stuff that’s easy to overcome–or at least easy to make a plan to overcome. When you start seeing the same spikes on multiple laps, however, that could point to a bad habit or an actual problem with the car. Add that investigation to your list.

Now Go Win

Armed with this cheat sheet and a simple graph that any $30 data program can produce, you’ve now got the tools to address many of the driving errors that can be exposed through quick and easy data analysis.

And we haven’t even explored additional channels yet. Having multiple channels of data to pore over between or after sessions is great, but it can also lead to analysis paralysis, especially if you’re just starting out with data. 

Start with a simple speed/distance chart and don’t overwhelm yourself. You may be surprised at how much info you can quickly access with a simple, two-axis graph.