Oli, I can pull that up on my home computer through our library using FLIPSTER
(viewable online magazines).
With your month/page information, CR is discussing GPS loaded into various cars. It is rating the car's GPS, not an independent GPS you buy and plug into the car.
Is this what you're looking for, because it specifically evaluates cars.
Best GPS in cars are Tesla (well, for that price, the car should come with its own sherpa), Audi, Ford, Chrysler, Kia.