A Flawed Masterpiece: the Marcos Mantis XP

One of the great “what if” moments in automotive history, the Mantis XP showed up in 1968 looking like it had just arrived from 2068, showing endless promise for the future of Marcos, a tiny British car company who had been making a name for itself in racing since 1959. With the XP, Marcos truly came out swinging with a punch that was far above its weight category. The question was: could Marcos land it?

The Mantis XP (as in “Experimental Prototype”…and they really weren’t kidding about that experimental part) was Marcos going way out on a limb. Yes, the company had some experience on the track, but something like the Mantis was so far removed from their previous stuff that it really isn’t surprising at all that, in the end, what really got the Mantis was a lack of some lengthier, more thorough testing and development.

Designed and built by the Adams brothers, Dennis and Peter, two blacksmiths with a tiny shop aptly named “The Forge”, right next door to the “Three Horseshoes Pub” (you couldn’t make this kind stuff up if you tried) on Bradford-on-Avon, Wiltshire. The Forge was specialized on wrought iron ornamental artwork, so a car was slightly outside the Adams’ typical body of work, but they made it happen, building the basis for the XP right above their regular workspace at The Forge. In the end, this proved to be a challenging option because when it came time to get the car out, it wouldn’t fit. So they had to resort to cutting the upstairs floor, you know, as one does when one’s building a Le Mans racer at a smithy’s attic. The central cell was made out of plywood (with wood chassis being a recurring practice for Marcos), coupled to steel-tube sub frames at the front and rear.

The engine was a Formula 1 derived Brabham-Repco V8 that Marsh had purchased from Jack Brabham himself. According to statements from Marsh in a 2009 article on Classic & Sports Car magazine, this wasn’t the original plan for the Mantis, as he had his eye on a 365bhp, 3.0L BRM V12, first debuted in 1967 on the McLaren M5A. However, the engine was too pricey and Marsh felt like it wouldn’t even be delivered on time, so the V8 became the alternative. It was then coupled to five-speed transaxles and suspension for the Mantis was provided by John Cooper, straight from the previous year’s Formula 1 car.

Calling the Mantis XP’s looks dramatic is a gross understatement. The massive front end shovel wedge, the radical Kamm tail, the roof mounted rearview mirror, the copious amounts of acrylic (Perspex, specifically) which make the cockpit look like it was pulled straight from a fighter jet…it’s simply one of the best looking, most original race cars ever made. Simultaneously defined by strong angles and subtle curves, the sheer complexity of the Mantis’ shapes is something which we’re sure that not even whole academic thesis could tackle properly.

The XP went through some testing at Castle Combe and Silverstone before making its way, in May of 1968, to Spa. A prelude to Le Mans, the Mantis had to prove that it had what was needed to eventually become a serious contender for the Group 6, 3.0L category at la Sarthe. It’s not like it was ever subtle, but the originality of the XP’s looks truly stood out when compared to the other racers at Spa; there was just nothing like it then and nothing like it has come along since.

Unfortunately, things started off rough and went downhill from there. The car qualified well over a minute and a half from pole with Jem Marsh at the wheel, a last minute decision as he could barely get in the car; the XP had been built around the considerable shorter Peter Adams, and Robin Widdows, the race driver who was supposed to pilot the Mantis, backed out, so Marsh ended up having to pull out the upholstery just to be able to fit in. The ambitious car’s debut was made under the worst conditions possible, with pouring rain putting Marcos’ build quality to the test. It failed. Badly. The big Perspex doors did not seal in any way shape or form and after a single lap, the car’s interior was flooded, forcing Marsh to go for an emergency pit-stop in which a hole was hastily drilled in the chassis so the water could drain out. The irony of a car made in Britain not fully taking into account the effects of rain is nothing short of extraordinary. Not only were the doors Perspex, but also the engine cover, which meant water was getting into the engine compartment about as fast as it was getting into the cockpit and wreaking all sorts of electrical havoc in the process. The most badly affected component was the alternator; it sat way at the back with little to no protection and it took some serious damage.

The first lap pit-stop had sent the XP to the back of the field and the next ten laps were spent crawling its way back up, making up an impressive 17 positions. However, the water damages were increasingly severe and Marsh knew it was imperative to preserve the engine; as such, he made the decision to abandon. And just like that, the Mantis’ racing career was over mere moments after it started.

Back home, the F1 engine was removed and replaced with a Buick V8, after which Marsh began to drive the car around on the streets (can you imagine it?). This caused an issue because, according to the government, the Mantis had to be taxed and because it wasn’t in any way a production vehicle, Marsh stated that the value of the car had been determined by the government itself, then calculating a tax based on that; reportedly, it was quite a significant one. So Marsh decided to send the car to the U.S., where it was displayed at the 1970 L.A. Auto Show. There, an enthusiast named Tom Morris fell in love with the XP, bought it and the Mantis has been kept in the family ever since, fully street legal and happily driving around L.A. and so-Cal.

However, in the early 00’s, the XP was understandably starting to feel the weight of four decades of use. Ned Morris, Tom Morris’s son began to address some of the most pressing issues, which – of course – ended up turning into a whole restoration process. When it was done, the car was shipped back to the U.K. for Marcos’ 50 years anniversary celebration at the 2009 Prescottt Speed Hill Climb, where it certainly made a splash (no pun intended). Afterwards, the Mantis also made an appearance at the ever popular Goodwood Festival of Speed in 2010, cementing its re-introduction to the world and becoming a crowd favorite.

The Mantis XP story is incredibly bittersweet. On one hand, knowing that the car’s potential was never realized is tremendously frustrating, more so because it barely had a chance to go out on the track and it immediately faced the very worst conditions. There’s no telling how far it could have gone with further testing, further development, better sealing on the acrylic panels…its ability as a Le Mans racer will always remain a giant question mark and that’s just tragic. On the other hand, it’s a heartwarming example of one family’s devotion to a car; Morris fell in love with it, his children fell in love with it, grew up with it, and for the last five decades, it’s been a member of the family. It’s been driven, enjoyed; it put smiles on the faces of people who watched it just casually driving down the street and as far as a car’s legacy goes, making people happy is not a bad one at all.