Many Nissan enthusiasts regard it as a tragic loss that the Mid-4 concept of the late 1980’s never reached production, despite extensive development and some very favourable reviews in the media. However, the Mid-4 wasn’t Nissan’s only still born mid engined sports car. A decade earlier, in 1975, the Nissan AD-1 had gone on public display for the first time but despite getting positive feedback, it never reached production. The AD-1 was a neatly styled and economic little two seater coupe with a mid mounted transverse engine, a recipe which would be repeated with Toyota’s MR2… but not until until some nine years later…

After Nissan’s experimental, rotary powered Datsun 1200 Coupe was killed off by the fuel crisis in ’73, the company needed a new direction for a small sports car. one that was a little cheaper and more fuel efficient. First though, they needed a fresh and contemporary shape, Ideas were initially penned as a series of rough sketches and renderings which were present to management by chief designer Toshio Maezawa and Itaru Sugino.

Based on these they were given to go-ahead to take the ideas further, but the team took a rather unorthodox approach. Rather than developing the car through ever more detailed drawings, they simply got together and had a chat, then busted out the modelling clay. In a very hands-on method, the team of designers at Ogikubo Works constructed several different clay models, with varying approaches to the styling, in 1:5 scale. These model also got to spend a few hours in the wind tunnel, with the final design achieving remarkably good aerodynamics, having an astonishing 0.26 Cd, remarkable even by today’s standards.

The slippery shape, allied to the low kerb weight of just 740kg, would have helped the car to give quite lively performance, whilst utilizing a relatively small and economical engine. The final design opted for fixed headlights, rather than pop-up units, partially to reduce costs, but also so as to not compromise the aerodynamics when they were in use.
Other details were ironed out too. Gone was the early proposal for a fastback, as this not only made engine access awkward, but had the potential to allow unacceptable levels of engine noise into the cabin. Instead, an upright rear glass was employed between heavily buttressed rear pillars. These helped to make a cantilever roof design possible, which in turn allowed for ultra-slim A-pillars and that massive curved windscreen.

With the construction of a full sized clay mock up, the final shape was completed, and from this a full size buck was made from which to mold a fibreglass bodyshell. This was mounted to a steel chassis, but only for the purposes of development and eventual display at the Tokyo Motorshow. The intended final production version would use an all steel monocoque body.

Outside, the car featured a luggage compartment at the rear, as well as more storage under the bonnet at the front and behind the seats. The doors featured a simple release button with a hand cutout, rather than full door handles, similar to the design used on the Renault 5. Unusually for a Japanese car of the period, the AD-1 also featured chrome, door mounted mirrors rather than the more common fender mounted mirrors which were still in use on most Japanese production cars of the day. This was possibly as a result of Nissan’s previous work with Experimental Safety Vehicles (ESV’s), as most likely were the colour coded, impact absorbing bumpers and the well protected, mid mounted fuel tank. The AD-1 also featured a lift out roof panel and a fold down rear window for open air motoring.

The interior of the AD-1 was functional rather than luxurious. Its most notable feature were the unique sports seats, which were described as “infinitely adjustable”, having an adjuster to alter the angle of the front of the seat squab, as well as a separate one to change the angle of the upper half of the backrest and headrest. The doors used a frameless design and the glass opened with manual winder handles. The dash sported a high set binnacle and low fascia to make the interior feel less claustrophobic, and initially employed digital instruments.

With the AD-1, reworking the standard drivetrain and suspension from everyday production models to make an affordable and fun sports car was the plan. Remarkably this was exactly the same route Toyota took many years later with the MR2, which is largely made up of humdrum Corolla and Tercel oily bits. The results were highly effective. The AD-1 re-purposed N10 Pulsar (Cherry) parts, even utilizing its 1.4 litre, overhead valve A14 engine, although equipped with electronic fuel injection and a 5 speed gearbox.

Mid mounting the A14 meant cooling the unit via long pipes to a small front mounted radiator, but whilst more complicated to build, this left the body sides free from unnecessary air intakes, while excess engine compartment heat was vented through grilles in the engine compartment cover, behind the rear window. Underneath, the car was independently suspended by struts all round and featured dual circuit, four wheel disc brakes. While these technical details might seem unadventurous today, it was a really high specification, especially for a small Japanese car in 1975.

The fully functional AD-1 went on public display at the 21st Tokyo Motorshow in 1975, resplendant in bright yellow and looking like a production ready vehicle. Most concept cars like this are merely a fanciful styling exercise, but it does appear that Nissan were serious with the AD-1, as not only was it a functional car, it featured details such as badges, locks and side repeaters… all items usually left off of concepts so as not to spoil the lines. Inside the the car looks every bit a production model and lacks the futuristic appearance seen on most concepts. The final car even featured practical analogue instruments rather than the early development car’s digital ones. So what happened?

Maybe Nissan were really close to building it for real, just as they were a decade later with the exotic Mid-4, but got cold feet at the last moment? Too costly to develop further or to construct perhaps? Maybe they considered that it may simply steal customers away from its existing coupes, such as the PB210 Sunny Excellent, KP710 Violet and the New Silvia S10? I guess we will never know for sure, but either way it was probably a great opportunity lost for Nissan, especially when you consider the success of one other very similar design from the same period, the Fiat X1-9 and the MR2 nearly a decade later. It’s also a sad loss for all of us too. Who wouldn’t fancy having one of these sat in their garage now?

2 thoughts on “1975 Nissan AD-1

  1. Big Hat says:

    what if any of this projects innovations trickled down into a production nissan?

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  2. RatDat says:

    Very litle from what I can tell. The biggest effort seems to have gone into the aerodynamics which Nissan doesn’t seem to have bothered about too much on the following decades production cars. Aside from the midship layout there’s not a lot of new thinking in the chassis. That’s why it seems likely the AD-1 was more a serious proposal for production than just a showcase concept.

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