Honda raised eyebrows last month at the Frankfurt Motor Show when it introduced a stunning concept called Project 2&4 that bridges the gap between cars and motorcycles. BMW had a similar idea in 1995 when it built an outlandish-looking design study dubbed Z18.

The Z18’s story began when BMW’s motorcycle-building division noticed that dirt bike sales were steadily going up after years of remaining relatively flat. The company’s top brass was surprisingly open to the idea of building wild concepts in the early 1990s because they were trying to expand into new segments after selling almost exclusively sedans and coupes for decades. Consequently, BMW Technik — an independent think tank with close ties to the Munich-based car maker — was asked to build a leisure-focused prototype that could be qualified as half car and half dirt bike.

When viewed from the front, the Z18 bore more than a passing resemblance to the Z3 roadster that was also introduced in 1995. Like the roadster, it featured a long hood that gently sloped down towards the top of the bumper, but it was equipped with four round headlights that created a visual link with BMW’s Enduro bikes. The back end was characterized by a concave rear fascia, elongated horizontal lights and, somewhat surprisingly, an elegant-looking piece of chrome trim around the license plate.

Because it wasn’t fitted with a top, the Z18 featured a rather Spartan cockpit with water-proof bucket seats, rubber floor mats and a back-to-the-basics instrument cluster made up of three round gauges (another styling cue borrowed from the world of motorcycles) that were mounted in the middle of the dash and clearly oriented towards the driver. Interestingly, the concept could be configured as a two-seater, as a four-seater, or as a pickup.

Power was provided by a V8 engine that sent 355 horsepower to all four wheels via a five-speed manual transmission. Official performance specifications weren’t published, but the roadster likely boasted a good power-to-weight ratio because its body was crafted entirely out of plastic and mounted on a lightweight steel frame. The generous amount of ground clearance as well as the high approach and departure angles suggest it was fairly capable off the beaten path, too.

The Z18 was never seriously considered for production and it remained a one-off design study; in fact, BMW didn’t show it to the public until about five years after it was built. However, executives were so attached to the idea of launching a more leisure-focused model that work on what would become the very first X5 (called e53 internally) began shortly after the Z18 was completed.

In other words, every so-called Sports Activity Vehicle (SAV) that BMW sells today traces its roots back to the fact that dirt bike sales were on the rise about a quarter of a century ago.

Photos provided by BMW’s archives department.