ThrottlePass Z-Score — Isolating for Driver Skill

A Smarter Way to Measure Lap Performance

Every lap tells a story — but not all stories are told on equal terms. A 1:32 in a stock Miata means something entirely different than a 1:32 in a 600-horsepower Corvette. That’s why we built TPZ — a new performance-normalized scoring system in ThrottlePass that goes beyond raw lap times.

What Is TPZ?

TPZ (ThrottlePass Z-Score) measures how well you performed relative to the expected pace for your car and setup — not just how quick your stopwatch says you were.

In simple terms:

TPZ compares your actual lap time to what’s statistically expected for your vehicle’s performance level, and then normalizes that difference by the expected variance at that level.

This means two drivers in wildly different cars can now be compared on the same playing field — their driver performance.

How It Works

Baseline Performance Model
Every track has an expected lap-time curve, built from real user data and simulation models that account for horsepower, weight, tires, and other modifiers.
Residual Calculation
Your lap’s deviation (the “residual”) from that expected curve is expressed as a percentage — how much faster or slower you were than predicted.
Normalization (Z-Score)
That residual is divided by the expected standard deviation at your performance level — meaning your score reflects not just how much you beat expectations, but how significant that result is statistically.

Constantly Learning, Constantly Improving

Like a good driver, TPZ keeps getting sharper with seat time.

As more laps are logged on ThrottlePass — across different tracks, vehicles, and setups — the underlying models recalibrate automatically. This ongoing feedback loop refines expected lap-time curves and variance estimates, making TPZ more accurate and fairer over time.

That means your future scores are benchmarked against an ever-smarter model that reflects real-world driving conditions and evolving car performance data from the entire community.

Reading the Leaderboard

You can now sort leaderboards by either:

Raw Lap Time — the classic measure of outright pace.
TPZ Score — a normalized measure of driver skill and consistency.

Under each TPZ score, you’ll see a delta to leader in seconds that is needed to match the current leader’s TPZ.

Enter Accurate Car Data for Fair Scoring

If you’ve modified your car — tuned, swapped, boosted, or lightened — make sure your lap entries reflect that.

Head back and edit your laps to include your actual horsepower, torque, and weight figures so that TPZ can fairly evaluate your performance. When these fields are missing, but you’ve toggled on modifiers like ECU Tune, Forced Induction Upgrade, or Engine Swap, the algorithm has no choice but to apply aggressive power-scaling assumptions to estimate your performance level.

That means your TPZ could be undervalued — not because you drove poorly, but because the system is compensating for unknown data. Supplying accurate specs ensures your laps are scored on true performance, not generic assumptions.

Why It Matters

TPZ makes competition fairer and more insightful:

It rewards driver skill, not just horsepower.
It levels the playing field across builds, budgets, and classes.
It helps you track your progress as a driver, not just your car’s.
And thanks to continuous learning, it only gets smarter and more precise with every lap uploaded.

TPZ will be the fundamental underpinning to our Challenges feature — coming soon!