Mk. III, 2005.5, B5...Which Golf, Jetta, Or Passat Do I Have?
Mk? Mark? What's in a generation?
New cars tend to be grouped in to "generations" when they come out: a car will use generally the same mechanical underpinnings (engine, transmission, and chassis) for a span of 5-10 years. You'll see minor year-to-year styling and options changes to keep it fresh over that time while new platforms and drivetrains are being developed for the next generation.
These relatively minor year-to-year mechanical changes make it helpful to know which generation your car is when picking parts. For instance, window regulators for a 2002 Passat will be the same as on a 2004 Passat, as they're both B5.5 generation cars.
VW's Golf, Jetta, and Passat are some of the longest-lived automotive nameplates out there, so even allowing for 5-10 years per generation, there have been quite a few different generations over the years. VW enthusiasts like to refer to generations as "marks", with the 1st generation being the Mk. I, the fourth generation being the Mk. IV, and so on.
Cars sharing platforms, like the sedan/wagon Jetta and the hatchback Golf, are typically referred to by the same mark because of the shared mechanicals.
Knowing your car's generation is important in cases where different models got updated at different times. For example, the Mk. V Jetta came out in 2005, but its platform-mate, the Golf, didn't get updated until 2006; in 2005, you could therefore get a Mk. V Jetta but only a Mk. IV Golf/Rabbit.
Half Model Years
Here at WPD, we've done most of the research for you, so for most model years you'll end up with the right parts for your Mk. IV Jetta just by plugging your year, make, & model in to our website's vehicle filter.
However, there are some cars for which VW's updates from one platform/generation to the next don't cleanly line up with a model year. For example: VW released the new generation of the Jetta partway through 2005, so you might have a Mk. IV or a Mk. V if you have a 2005.
Where these part-year updates happen, people often like to give the newer version a ".5" model year label, and you might see us call a 2005 Mk. V Jetta a "2005.5" to help distinguish it from an early 2005 Mk. IV.
We've created this guide around these tricky 1999-2006 model year cars where the ".5" overlap is the most common, to help you pick the right mark for your car.
Jetta: Mk. III, IV, and V
The Mk. III has a styling "crease" line running from the front of the car to the rear, visible between the windows and door handles. It's more angular (especially at the rear roof) and has turn signals and other secondary lights below the headlights in the front bumper.
The Mk. IV is more rounded, with a rear roof section that gradually curves down. It has angular/trapezoidal headlights with the turn signals in the inner corners, fender mounted side marker lights, and a stubby radio antenna sticking up at an angle from the rear roof.
The Mk. V is more rounded still, with round instead of angular headlights, turn signals integrated in to the sideview mirrors, and a large U-shaped chrome accent in the front bumper surrounding the grille.
Golf: Mk. III, IV, and Rabbit V
Like its Jetta platform mate, the Golf (called the Rabbit in the Mk. V generation) had some half-year model updates, though with its more conservative styling updates compared to its sedan cousin, you'll have to look a little closer to spot the differences:
The Mk. III has headlights which are round on the inside, secondary lights (turn signals) in the bumper below the headlights, and a styling "crease" line running from the front of the car to the rear, visible between the windows and door handles.
The Mk. IV has oblong side market lights on the front fenders and headlights rounded at both ends, as well as an angled, stubby radio antenna sticking up from the rear roof.
The Mk. V is more rounded still. Only the GTI has the two-tone grille accent like the Mk. V Jetta, but all Mk. V Rabbits share the Jetta's round-with-a-flat-bottom headlights and side mirrors with integrated turn signals.
Passat: B4, B5, B6
Passats are VW's midsize car compared to the smaller Golf and Jetta, so they have some divergent evolution as far as shared parts and platforms go. This was especially apparent in the B5 generation from 1998-2005.5, where the Passat shared a platform with the Audi A4. Starting with the B3/B4 Passat, the platform names VW uses internally for these cars became enthusiast shorthand for their generations
The B4 Passat, like other 90s VWs like the Golf and Jetta, is pretty angular. It has secondary lights in the bumper below the headlights, square side market lights on the front fenders, and an angular rear roofline.
The B5 Passat is much curvier, with a curving roofline from front to back, round side marker lights on the front fenders, and two-piece reflector headlights.
The B5 got a styling refresh halfway through its life, so 2001.5-2005 Passats are referred to as B5.5 Passats. They have one-piece projector headlights, chrome front bumper trim, and front bumper reflector strips on either side near the wheels.
B6 Passats look a lot like big Mk. V Jettas, sharing the same chrome grille accent and side view mirrors with integrated turn signals, as well as one-piece headlights with a little "scallop" cut in to the bumper for the low beams.