For the Tesla nerds. Every number on your dashboard, the exact formula behind it, and where the data comes from — no black boxes.
Where the data comes from
The data pipeline
Your car is the sensor. We collect its data two ways and merge them:
Fleet Telemetry (primary). Your Tesla pushes data to us over an encrypted connection whenever it's awake — driving, charging, running climate, or during its own periodic wake-ups. It costs a fraction of polling and never disturbs the car.
Poller (fallback). If Fleet Telemetry goes quiet while the car is awake, we briefly fall back to asking Tesla's API directly. We never force-wake a sleeping car — a parked, sleeping Tesla reports nothing, by design, to protect your battery.
Fleet Telemetry arrives as sparse updates: each message carries only the signals that changed. To rebuild a complete picture at any moment we use a forward-fill: every field shows its most recent real reading until a newer one arrives.
state(t) = last non-null reading of each signal at or before time t
(merged across Fleet Telemetry + poller)
So a "complete" row is reconstructed, not assumed — if your tire pressure was last reported an hour ago, that's the value we show, not a guess.
Driving
Trips
We group consecutive driving samples (gear in Drive or Reverse) into a trip, splitting whenever there's a gap longer than 10 minutes, and we drop anything under 60 seconds.
trip distance = odometer(end) − odometer(start)
start / end place = first / last GPS fix within the trip window, reverse-geocoded
Distance comes from the odometer, not from summing GPS points — the odometer is the car's own measurement and avoids GPS drift. Tesla streams location and gear in separate messages, so we match each trip's coordinates to its time window rather than expecting them in the same row.
Tesla doesn't stream "energy used," so we measure it. Two steps:
1. Figure out your usable battery size from your own charging history — how many kWh it took to raise the charge by a given percentage:
usable pack (kWh) = average of [ session kWh added ÷ (% gained ÷ 100) ]
over charge sessions of at least 10%
2. Measure the energy actually spent driving — the charge dropped while the odometer was moving, converted to kWh with that pack size:
drive energy (kWh) = (% dropped while driving ÷ 100) × usable pack
efficiency = miles driven ÷ drive energy → mi/kWh
consumption = drive energy × 1000 ÷ miles driven → Wh/mi
cost to drive = drive energy × your $/kWh ÷ miles driven → $/mi
Why not just miles ÷ kWh charged? Because that "wall-to-wheel" number folds in parked drain, climate, and charging losses — for a lightly-driven car it can read nearly double the real figure. We deliberately count only energy spent moving, so our mi/kWh tracks the number on your car's screen.
Charge cost uses your energy rate if you've set one (Energy rate card); otherwise a flat $0.15/kWh estimate.
Source: charge sessions (for pack size), state-of-charge & odometer while driving. Pack size is self-calibrating — no hard-coded battery spec.
Charging & battery
Charge sessions
Consecutive Charging samples become one session, split on gaps over 30 minutes.
energy added = per-session "charge energy added" (Tesla resets it each session),
or, from Fleet Telemetry, the rise in the cumulative AC + DC energy meters
peak power = highest kW seen during the session (over 20 kW → labeled DC fast charging)
Source: charging state, energy counters, charger power (Fleet Telemetry + poller).
Battery health (degradation)
Tesla's rated range is already scaled to your current charge, so to compare fairly over time we project it to a full 100% pack:
full-pack rated range = rated range ÷ (state-of-charge ÷ 100)
degradation % = (1 − current ÷ best day ever) × 100
We average many readings per day, exclude charging and readings below 20% (where the projection is least reliable), and baseline against the best day we've ever recorded — an honest, self-contained reference rather than a marketing "new" figure. Degradation is a months-to-years signal; expect it to look flat at first.
Battery lost while parked — sentry, cabin-overheat protection, sleep overhead. The trick is proving the car wasn't driven:
count a % drop only when the ODOMETER DID NOT CHANGE between two readings
intervals between 5 minutes and 8 hours apart (readings sampled per 15-min bucket)
drain rate = total % lost ÷ total parked hours
The odometer guard is what makes it honest — without it, two "parked" readings that secretly bracket a drive would report a huge false drain.
Source: state-of-charge, odometer while parked.
Tires & taxes
Tire pressure (TPMS)
Tesla reports pressure in bar; we convert to PSI and flag anything low.
PSI = bar × 14.5038 (low-pressure flag below 38 PSI)
Tag each trip business or personal; we total the miles and estimate the IRS deduction.
business deduction (estimate) = business miles × IRS standard rate
IRS standard rate = $0.70 / mile (2025)
This is an estimate to help your records, not tax advice. The IRS standard mileage rate changes yearly; confirm the current rate and your eligibility.
Source: trip distances + your business/personal tags.
Constants & honesty notes
Constants & honesty notes
IRS standard mileage rate
$0.70 / mile (2025) — used only for the deduction estimate
bar → PSI
× 14.5038
Default energy rate
$0.15 / kWh, until you set your real plan
Trip split / min length
> 10 min gap splits; < 60 s dropped
Charge-session split
> 30 min gap
Phantom-drain window
5 min – 8 h between parked readings
A few things we want to be straight about: state-of-charge is reported in whole percent, so very short trips are noisier than long ones; efficiency and cost are most accurate over a week or more; and anything labeled an estimate (deduction, charge cost without a set rate, pack size) is exactly that — derived from your data, not a spec sheet.