Gas Math

Gas Math. Gas Math. Gas Math.

Get a cheap OBD dongle from Amazon and read useful data from your car. Math it up with stats from your phone to accurately calculate your fuel efficiency, and get analysis and coaching on how to adjust your driving to save up to 25%1 on CO₂, fuel, and thus cost.

Also know when your engine's overheating, your battery's dying, and when the check-engine light is serious this time.

* Also works without the dongle, just not as accurately.

Coming soon to the App Store. iPhone only.

Gas Math replaying a hard right turn: a red-hot marble at 0.38 g, with a trail behind it cooling from orange to green.

What it does

  • Coaching you can hear

    A soft tone and a buzz when you press too hard or brake late. Quiet when you drive well, and never a constant beep.

  • Drive reports

    How smooth each drive was, your best streak, and what hard throttle and hard braking cost. Same trip as usual? It shows how this one compared.

  • Fill-up calibration

    Log fill-ups and Gas Math tunes its fuel estimates to your real receipts. It can spot a fill-up from the tank gauge, too. Fuel and cost figures are always marked as estimates.

  • Stats

    Week by week: how smooth you drive, your fuel use, engine heat, and the money lost to hard pedals.

  • Check-engine codes

    Reads the car's trouble codes at the start of each drive, and explains the common ones in plain words.

  • Battery and engine heat

    Warns when the battery is low or not charging, and when the engine runs hot.

  • Mileage log

    Mark drives as business and export a CSV for your taxes, with odometer readings for the year.

  • Household leaderboard

    Share the car with someone? Link drivers through iCloud for a weekly leaderboard and shared fill-ups. Routes stay private.

A look inside

  • The Pedal view during a drive: a big green Smooth label, a pedal bar between Ease off and Brake, 100% smooth and a 33-second streak.
    One big signal while you drive.
  • The Coffee view replaying a hard turn: a teal mug of coffee sloshing, with two spills on the saucer.
    Or drive like there's a full cup on the dash.
  • Home screen: This week, 93% smooth over 28 km and 6 drives, 16.0 L/100 km estimated, $0.57 lost to hard pedals, and a Start driving button.
    Your week at a glance.
  • Stats screen with charts of smooth driving per drive, estimated fuel use in L/100 km, and dollars lost to hard pedals per week.
    Trends over weeks, not just one drive.

What you need

Best: an OBD adapter

Works with the Veepeak OBDCheck BLE. It plugs into the port under your dashboard (most cars from 1996 on) and talks to your iPhone over Bluetooth.

Gas Math then reads speed, engine speed and throttle straight from the car.

Or: just your iPhone

No adapter? Gas Math still coaches you using the phone's GPS and motion sensors.

Estimates are rougher without engine data.

Gas Math is not made by or affiliated with Veepeak or Amazon. These links earn us nothing.

Private by design

No data collected. No account, no ads, no tracking. Your drives stay on your phone, or in your own iCloud if you link other drivers. Read the privacy policy.

  1. Natural Resources Canada says fuel-efficient driving can lower fuel use and CO₂ emissions by as much as 25%, and that many drivers use 15% less fuel by acting on fuel-use feedback. Your savings depend on how you drive now. ↩