Looking for a Dragy alternative?

Straight answer: a dedicated GPS box like a Dragy samples faster and more consistently than a phone, so for a single number in isolation it is more accurate. AsyncRacing is a free iPhone app that adds the things a box does not do — correcting every run to standard air, and racing your recording against other people's.

Where a dedicated box genuinely wins

It would be dishonest to pretend otherwise, so here it is plainly. A Dragy-class device has a GNSS receiver that samples faster than a phone's, it sits in a fixed position with a clear view of the sky, and it has one job with nothing else competing for the hardware. Phones vary considerably between models, and the same phone can behave differently depending on where it is mounted and what else is running.

If your question is "what is the single tightest number I can get for this car," a box is the better tool. That is what it is for.

Where a box leaves you on your own

A box gives you a number. It does not tell you what that number was worth. A 12.4 run in hot, thin summer air and a 12.4 on a cold, dense night are not the same performance, and unless you are doing the correction yourself you are comparing weather as much as cars.

It also does not give you anyone to race. You get a list of your times, and perhaps a leaderboard to look at. There is no head-to-head, no matchmaking against cars near your pace, and no reaction-time element — which for a lot of people is the actual fun of drag racing.

What AsyncRacing adds

• Every run corrected to standard air. The app pulls the real conditions for where and when you ran and restates the pass on a common reference day, so your July and your November are comparable. How that works →
• Racing, not just recording. Your recorded run becomes a ghost other people can line up against — and the tree is live, so your reaction time is a real skill that decides real races.
• Class matching. You are paired against cars that actually run near your pace, based on what they have recorded rather than what anyone claims.
• Measured power. A wheel power and torque curve derived from the run itself, with the gearshifts visible in it. More →
• Free, and nothing to carry. The phone is already in your pocket.

An honest limitation

Phone capture accuracy is the hardest part of this, and during the beta it is still being tightened — some runs on some handsets have reported times that were clearly wrong. Every result screen has a diagnostic export precisely because that is a real problem being worked rather than one being papered over. If a tight, trustworthy single number is what you need today, buy the box; we would rather say so than oversell.

So which should you get?

Buy a box if you are chasing records, validating a build, or need numbers you will quote to other people as fact.

Use the app if you want to know whether a modification helped, see where your car really sits once the weather is accounted for, and actually race people rather than compare screenshots. It costs nothing to find out.