All iPhones except the first generation come with an internal GPS sensor and can be used for lap timing out of the box. However, if you are interested in higher accuracy and use LapTimer a lot, I recommend the use of an external GPS accessory. For iPod touch devices and iPads (non-3G) it is a different story. They do not have an internal  GPS sensor (network triangulation only) and thus cannot be used without additional sensor support.

This page discusses several solutions available in the market. Only a small number of combinations is supported from my side. As the battery drains fast with all features enabled, an external power supply is recommend in all configurations.

1. ✦Works out of the box
   

2. ✦AGPS, fast initial acquisition
   

3. ✦Pretty good on 4G, 4GS, 5
   

4. ✦Comes "for free"
   

1. ✦Limited position / timing accuracy
   

2. ✦Problems with high speeds
   

3. ✦No GPS for iPod touch, iPad Wifi

1. ✦Inexpensive for a Wi-Fi device
   

2. ✦Standard ELM 327 communication
   

1. ✦Due to Wi-Fi usage, high power consumption for iPhone / iPod
   

2. ✦Uses AdHoc Wi-Fi mode blocking parallel connections (e.g. GoPro)

1. ✦Standard ELM 327 communication
   

2. ✦Supports several network configurations, thus allowing other
   Wi-Fi devices to work in parallel
   

3. ✦Fastest OBD adapter available
   

1. ✦Wi-Fi configuration necessary
   

2. ✦Due to wifi usage, high power consumption for iPhone / iPod

1. ✦Very good positioning accuracy
   

2. ✦iOS and other devices supported
   

3. ✦5 Hz update rate available
   

4. ✦High timing accuracy (real time)
   

5. ✦Satellites info available
   

1. ✦Additional investment ± US$ 100

1. ✦Very good positioning accuracy
   

2. ✦iPhone, iPod touch, iPad supported
   

3. ✦Reuse of existing GPS devices
   

4. ✦Full timing accuracy
   

5. ✦High update rates available
   

1. ✦Requires jailbroken device

1. ✦Very good positioning accuracy
   

2. ✦Power supply included (USB)
   

3. ✦iPhone, iPod touch, iPad supported
   

4. ✦5 Hz update rate available
   

5. ✦High timing accuracy (real time)
   

6. ✦Satellites info available
   

1. ✦Additional investment ± US$ 80
   

2. ✦Uses old 30-pin dock connector

Despite all the accessory discussions on my forum, and the ratings below, I receive questions on recommended configurations VERY frequently. So to make my life easier, here is my personal choice of devices. This section is regularly updated. Please note that today's best is probably second best tomorrow, so please don't make me responsible if things change ;-)

iPhone5 or later. As an inexpensive alternative, you may go for an iPod touch (5th generation or later) plus an external GPS.

Important: in case you plan to record video or use one or more external sensors at a time, an iPhone4S or an iPod touch 5th generation is the entry level currently. For video recording, please plan a 32 or 64GB device.

RAM Mount RAM-B-166U  (add the cradle matching your iPhone)

XGPS160 (10 Hz) for any iPhone (and other smartphones), or Racelogic's 20 Hz VBOX Sport for professional use

Yes, inevitable

No, that's evil; enjoy simplicity, or start programming yourself

GoPoint Technology's BT1(A) or - in case you prefer a wifi based dongle - OBDLink MX

1. ✦Parallel PID requests supported in LapTimer GrandPrix edition
   

2. ✦Seamlessly connected using Bluetooth, auto power off
   

3. ✦Mfi certified, compatible to all iOS devices
   

1. ✦Due to BT a little slower than Wi-Fi devices

1. ✦Very good positioning accuracy
   

2. ✦iPhone, iPod touch, iPad supported
   

3. ✦20 Hz update rate available(*)
   

4. ✦Designed for track use
   

5. ✦High timing accuracy (real time)
   

1. ✦Additional investment ± US$ 400

1. ✦Very good positioning accuracy
   

2. ✦iOS and other devices supported
   

3. ✦10 Hz update rate available
   

4. ✦High timing accuracy (real time)
   

5. ✦Satellites info available
   

1. ✦Additional investment ± US$ 150

For compatibility statements on our new Android version of Harry's LapTimer, please follow Android Compatibility. This page is on iOS compatibility only.

In case you want to know more about the options before you order from the links above, here are the details on the individual devices. This section starts with an introduction to GPS devices, for OBD dongles, please scroll down. But we start with some general directions one needs to understand when adding accessories to iOS devices:

There are some Partners I recommend to order the above devices from. This links are no "best price" benchmarks, but are based on my knowledge they will service you well. Important: using the links will initiate a contractual relation between you and my Partners, not between you and me (I'm not in the hardware business).

Order your XGPS from Dual Electronics Corporation.

Order your RAM Mount RAM-B-166U from Amazon Deutschland. Add either an iPhone4/4S cradle (RAM-HOL-AP9), or an iPhone5/5S cradle (RAM-HOL-AP11). For motorbikes, check the RAM-B-176 (plus cradle again).

For all other region / product combinations, please google as usual.

XGPS150A

XGPS160

Orders will be sent by FedEx ground, and orders can only be shipped to a US address. No P.O. boxes or APO addresses.

Order your PLX Kiwi Wifi 2 from Amazon Deutschland. As long as the GoPoint BT1(A) and the OBDLink MX wifi are not available, the Kiwi is the best option available in Germany.

Order your Dual XGPS160 featuring 10 Hz  update rate and full support by Harry's LapTimer from Amazon Deutschland.

Order your RAM Mount RAM-B-166U from Amazon. Add either an iPhone4/4S cradle (RAM-HOL-AP9), or an iPhone5/5S cradle (RAM-HOL-AP11). For motorbikes, check the RAM-B-176 (plus cradle again).

Order your GoPoint BT1 or your PLX Kiwi Wifi 2 from Amazon. The GoPoint BT1(A) is the only Apple certified BT OBD available. It receives special support by Harry's LapTimer.

Order your Dual XGPS160 featuring 10 Hz update rate and full support by Harry's LapTimer from Amazon.

Order either a GoPro HERO3+ Silver Edition or the GoPro HERO3+ Black Edition Outdoor from Amazon Deutschland. To remote control these cams fully synchronized with lap timing, Harry's LapTimer GrandPrix Edition is required.

Order either a GoPro HERO3+ Silver Edition or the GoPro HERO3+ Black Edition from Amazon. To remote control these cams fully synchronized with lap timing, Harry's LapTimer GrandPrix Edition is required.

This page discusses compatible devices for iOS devices. Although the page is focussed a lot on Harry's LapTimer, it applies to all other Harry's apps mostly too.

The page starts with our up to date recommendation named "Harry's Choice". It is followed by a collection of links to distributors we like. The details start in the next sections, they are grouped by device type:

Optional for all apps - additional data available from your car's bus

Relevant for all apps - improved accuracy and data richness

Relevant for Harry's Heavy Duty - Camper Edition

In case you want to see more details on connection technologies used for smartphones, please check an article I have made available on the forum:

[FAQ] Bluetooth, Wi-Fi, or Plug-in Accessories?

1. ✦Inexpensive
   

2. ✦Lots of sensors built in
   

3. ✦Incredible battery life time
   

4. ✦Allows distributed installation
   

5. ✦Easy to use
   

1. ✦Update rates and accuracies are lower than those of the sensors built into your iPhone

Optional for all apps but Buddy - better video quality than internal cam

Both GoPro and Sony cams are supported starting with v19 of all apps. GoPro's HERO4 Silver edition is probably the best choice.

1. ✦Incredible video quality
   

2. ✦Wide angle lenses
   

3. ✦Wide range of models to fit individual requirements
   

4. ✦Memory inexpensive to add
   

1. ✦Lousy battery life time
   

2. ✦Premium pricing

1. ✦Great video quality
   

2. ✦Wide angle lenses
   

3. ✦Wide range of models to fit individual requirements
   

4. ✦Memory inexpensive to add
   

1. ✦Lousy battery life time

1. ✦Custom integration including multi CAN requests (GrandPrix)
   

2. ✦Rich set of functionality beyond OBD–has its own app ecosystem
   

3. ✦Seamless connection using Bluetooth (Mfi certified)
   

1. ✦Works with customized apps only