Data Acquisition: Meaning Of Lap Time

Published: July 12, 2014

A lap time tells us how fast we are going, right? Yes, but there are many uses of the lap time beyond the obvious determination of whether driver X is faster than driver Y.

Comparison To Others

The most obvious use of lap time is comparing one's lap times to some reference times. This works very well for drivers of some cars and is largely useless to drivers of other cars.

An example of a meaningful comparison is an HPDE driver in a Spec Miata comparing their lap times to Spec Miata qualifying times. in this case the car being driven is the same, and the difference in lap time can be attributed primarily to driver skill1.

For most HPDE drivers, such a comparison is not going to be particularly favorable: where a Spec Miata lap record might be 1:30, an intermediate driver might lap the same course in 1:45. This can be depressing, but the thing to realize is that Spec Miata drivers who set lap records have not only a lot of experience, but who have a lot of experience driving their car. This experience cannot be obtained any other way than seat time, and being upset over lack of it is pointless. Instead, a useful metric to examine is the difference between one's lap time and the lap record in their car.

Time Behind Lap Record / Placement In Field

Continuing with our hypothetical Spec Miata example, a novice driver in a Spec Miata might post a 2:00 lap time2, an intermediate driver might post a 1:45, an advanced driver in a budget-prepared car might run a 1:35 and an advanced driver in a pro-built car might run a 1:30. Within Spec Miata racers though there are advanced drivers in budget-prepared cars as well as intermediate drivers. It is very possible that on a given day, qualifying times may range from 1:30 to 1:45.

By looking at the position of your lap time within the field, and difference to the top qualifier, you can track your driving skill progress over time. Initially you will be at the very bottom of the standings, eventually you will move to the middle, and some day you might find yourself at the top. If you have an idea of how well prepared your car is you can set realistic goals for your lap time.

When Fastest Lap Occurs

A reasonably good way of evaluating a driver's experience, confidence and aggression is to observe when they set their fastest lap in a given session.

A novice driver is normally not focused on lap time at all, and often varies their driving to the point where lap times are meaningless. For example, a novice driver might brake earlier than they were braking previously simply because they are now working on another element of the course and they forgot their established braking point.

An intermediate driver is consistent enough that lap times start to be meaningful. Intermediate drivers typically start sessions with low aggression and correspondingly slower pace and gradually increase their aggression and pace throughout the session. Given a typical 20-25 minute session, the lap times often would be steadily dropping until the 15-20 minute mark which would see the fastest lap. Then the driver would start getting tired and would reduce their aggression and pace, leading to lap times increasing again.

An advanced driver knows their car and is confident in their driving. After a short warmup, which can take as few as 2 laps, they are ready to drive at their customary aggression level. An advanced driver with good reference points will be able to run lap 3 the same way they would run lap 10 or 20. As such, the best lap time for an advanced driver can happen very early in the session.

Advanced drivers also are more prone to overheating tires - even R compounds - because they slide the car in the corners. If an advanced driver is using softer tire compounds, or is very aggressive, their tires may start overheating after as few as 5 laps. An advanced driver using harder tire compounds or limiting sliding to extend tire life may run much of a session within a second of their best time. Such a driver would quickly reach the ballpark of their best performance and stay there for an extended period of time.

Setting a quick lap early in a session is handy for time trial competition. I do not believe one can actively improve when their best lap happens though. The timing of the quick lap is a function of seat time, and drivers who continue driving naturally progress to setting fastest laps earlier.


  1. In reality, professionally built Spec Miata cars are significantly faster than budget built Spec Miata cars. An HPDE driver in a budget Spec Miata is unlikely to ever reach Spec Miata lap record times. 

  2. In reality, novice run groups have enough traffic that a driver would be hard pressed to have a clean lap at all.