Recently I reviewed the Magellan RoadMate 3000T, TomTom GO 910, and Garmin StreetPilot c550. All three units use SiRF's latest high performance 20-channel receiver, the SiRF StarIII. So you would expect all three units to have similar GPS performance. I did a side-by-side comparison, and found some surprising results.

Figure 1: Clockwise from the top-left, the Magellan RoadMate 3000T, Garmin StreetPilot c550, TomTom GO 910. The units were setup indoors, close to a window. Look at the difference between the TomTom 910 and the Magellan and Garmin -- both the Magellan and Garmin get 4 out of 5 bars signal strength, while TomTom's GO 910 only gets 2 out of 5 bars.

Figure 2: A closer look at the Magellan. Although the Magellan is considerably less expensive than the Garmin or TomTom (and not really a fair comparison here, since the Magellan 3000T would really compete more with the Garmin c530 and TomTom GO 510), it had considerably better signal reception than the GO 910, and was on par with the Garmin c550.

Figure 3: The Garmin c550 had similar GPS performance to the Magellan 3000T, and considerably better performance than the TomTom GO 910.

Figure 4: The TomTom GO 910.I was surprised at how much worse GPS performance was on the TomTom GO 910. Signal reception was almost half as strong on the 910 as it was on the Magellan 3000T or the Garmin c550.

Figure 5: A more detailed info screen on the Magellan RoadMate 3000T.

Figure 6: A more detailed GPS Status screen on the TomTom GO 910.

Conclusion: I would not have guessed it, but it turns out the TomTom 910 was the under performer here. The Magellan 3000T and Garmin c550 both had comparable performance, getting a strong 4 out of 5 bars even indoors. The TomTom GO 910, on the other hand, fluctuated between 2 bars and no signal at all.