The Volkswagen Type 4 was a strange member of the VW family. Some think it was the last attempt at continuing a technological tradition doomed long before. Others characterize it as the step between the "old" aircooled and the new watercooled models. It is a strange hybrid indeed if you look into the details.
On the one hand we have the well-known rear engine and rear wheel drive-layout with the 4 cylinder air-cooled boxer setup. All well known and proven by its predecessors. But we also have some startling new elements:
The unitized body design which does away with the old "body-on-chassis"-setup. It allows the VW engineers to introduce the first 4 door VW passenger car, the VW 411 4-door sedan.
At the same time the torsion arm axles are making way for far more modern McPherson struts up front and an independent suspension in the rear with coil springs and constant velocity joints joining the axle shaft to the transmission and the wheel.
The steering is of the recirculating ball-type, something only found in high-priced premium automobiles at that time.
Engine-wise the output was greatly increased by a jump in displacement. Many people assume the engine is very similar to or maybe even the same as the one still put into bugs and buses, just a little larger. But that's not true. The Type 4 engine was a brand-new construction, designed and built for this model. No part is interchangeable with the upright-fan Type 1 engine and trying to stuff it into a Type 1 is a nightmare (for all those who believe in quickie-solutions for increased engine power). Major and improved features include an all-aluminum crancase - used after an initial attempt to use the old magnesium alloy in the 1968 model "V" engines - which can be welded and remanufactured (the magnesium case used in the bug-engines is NOT suitable for rebuilding, align-boring, welding and such, even though backyard VW shops love selling you this service; this is officially stated by Volkswagen, and they use brand-new cases when doing factory rebuilds as well), a real full-flow oil-filtering system with a replaceable filter element, and a layout with plenty of reserves for increasing displacement.
Creature comforts were another important aspect under which this car was designed. A ride smoother and, above all, quieter than the VW Type 3 was achieved with superb insulation and a redesign of intake and exhaust systems along with the new engine.
A remarkable standard feature was the Eberspächer gas-electric heater. In conjunction with the engine heating system and its own auxiliary fan to make it independent of engine speed it provided a level of heating efficiency only surpassed by water-cooled automobiles. The gas-electric heater does not need the ignition to be switched on, it can be set to run all by itself for up to 10 minutes with the switch on the dashboard. As the passenger compartment is being warmed up by unseen magic the owner can have the last cup of breakfast coffee.
Another item on the long list of standard features is the fully automatic transmission. While the Type 3-buyer had to pay $850 to enjoy clutchless automatic shifting it was part of the package for the Type 4 wagon and 4-door sedan customer. The 2-door sedan, seen as the "sporty" choice, retained a manual 4-on-the-floor transmission. Even this manual transmission offered a feature not found on any other Volkswagen of that period: The clutch was actuated hydraulically instead of relying on a cable to transmit pedal movement.