In the events of the Fourth Holy Grail War, Kiritsugu has Maiya prepare a mechanical prop more fitting for guerrilla warfare than a car in the form of a Yamaha V-Max, a powerful motorcycle likened to a "steel lion", during the Fourth Holy Grail War. It has a ridiculously impractical and hypothetical design that ignores the limits of normal drivers. The motorcycle body, that of a Yamaha V-Max, is already the most powerful in the modern world, and the original V4 1200cc 140 Horsepower engine that could already work near its limits was strengthened again into a V4 1400cc engine. The acceleration system is completely reinforced to make it a monstrous abnormality with an output equal to 250 Horsepower. The structure of the V-style propelling mechanism and its four-cylinder design allows it to immediately start to work as a two-cylinder design when the limit of engine rotation is reached and allows it to increase the amount of air sucked in to achieve an ultimate acceleration.
It has surpassed the basic rule of a machine, the limit of "machines are tools of men." It can be thought of as an alien creation born through advanced modern technology which can only show its true worth by having an inhuman Servant rider. It is a design structure that would normally never be placed on a machine using two cylinders, but it is a "beast" that has completely surpassed the limits of a motorcycle. It can no longer function properly as a two-wheeled design because of the various extreme reinforcements. The wheels have too much torque, and they cannot generate enough friction with the road and only keep on turning. The front wheel jumps up whenever the brakes are applied, creating enough force to throw off the driver immediately. Its deepest hidden secret and most powerful trump card lies in a button on the steering wheel. It causes a valve inside the interior of the engine to switch to automatic mode and fill with oxide fuel. The nitrous oxide expands under the high temperature of three hundred degrees Celsius and reaches the boundaries of its limits to increase the V-Max's acceleration rapidly by twofold.
Saber, as a Servant, exists far beyond ordinary humans, so she is able to manage control over it with ease. Acting as her "steed", the speed it grants reminds her of riding a horse more than the Mercedes, and even though she is driving a creation of modern technology, riding it allows her spirit to return to the memorable battlefields of the past and regain the spirit of chivalry from a time when she had held her lance and charged towards the enemy formation. She becomes able to easily detect obstacles blocking her path through changes in the air flow, and even closing her eyes wouldn't hinder her ability to avoid collisions. She removes her armor because it would only hinder her riding, and because she is short in stature, she can only control the over three hundred kilogram, super heavily reinforced motorcycle in a precarious driving position. She is practically lying flat on top of the engine, which is covered by a plastic turbo pump, and is forced to bear the powerful vibrations of the large engine while holding onto the steering like a child desperately clinging onto the back of a beast.
She has no trouble controlling the physically uncontrollable steed perfectly at full speed from that position due to her prided battle skills and Mana Burst ability. She focuses the motorcycle's horsepower entirely on acceleration, and controls it with the enormous power of her mana bursts instead of breaking. As it was completely revamped to achieve the ultimate acceleration, it has no dexterity much like cars modified to compete in high-speed short and straight courses. Her superior skills allow her to overturn the common physical rule of "vehicles can’t turn corners at high speed", making it possible for her to open the throttle valves on tight turns to pour all of the excess torque into the back wheel. The intense acceleration would normally threaten to topple the vehicle sideways due to the front wheel starting to drift, but her explosive energy allows her to forcibly tilt it to the side in order to complete the turn. Rather than skill, it is more like using even more power to overwhelm and twist the direction of the vehicle.
Despite the machinery being extremely advanced, it is unable to cope with Saber's riding for very long. It easily reaches 6000 revolutions per minute from her breakneck pace, and on its own, it is able to reach over three hundred kilometers per hour. No mater how much of her magical energy she uses, the strength of its material composition and structure are limited to their original design. Before even catching up to Gordius Wheel, the machine has fully manifested all of its ability to its greatest capacity by that point, and the engine and acceleration system already show signs of breaking down. The ability to match something transcending normality like a Noble Phantasm requires to use both her armor and Invisible Air in conjunction to reinforce it and reduce the burden. This mode is called Saber Motored Cuirassier (セイバー・モタード・キュイラッシェ, Seibā Motādo Kyuirasshe?, Saber Motard Cuiassier). Through intense psychokinesis, she is able to fuse her own armor with the bike following a concept similar to the armor that protected beloved horses on the battlefield to turn the motorcycle into a "magical beast" with a hard structure befitting its extraordinarily strong horsepower.
The capability of the entire bike is increased due to being wrapped in the flexible and strong sliver armor, and she constantly releases her magical energy to reinforce, cover, and protect various important parts that are able to ensure maximum speed of movement. It also increases her unity of riding by truly making it into her own limbs. The speed causes air friction that is close to approaching the force of water pressure, so she releases Invisible Air in the shape of an arrow around her to completely cover the body of the vehicle. She is able to entirely release it from air resistance by decreasing it to zero with the compression of the pneumatic umbrella. This allows it to easily reach over four hundred kilometers per hour, and due to the pressure released by the magecraft, the back wheel is firmly pressed against the cement even when making turns at full throttle. She has full control even at this speed, allowing her to easily dodge and weave through numerous obstacles while only on one wheel.
 Fate/Zero material - Encyclopedia: YAMAHA V‐MAX [Other], p.105
YAMAHA V‐MAX [Other]
The motorcycle that Emiya Kiritsugu prepared for his Servant. Since it underwent excessive tuning without any regard for usability, a normal person trying to ride it would just end up killing themselves. Maiya must have brought it into town on a truck, then pushed it from the front gate to the courtyard.
The president of Nitro+, Digitarou, was responsible for picking out and configuring the vehicle model.
By the way, at one point during the consultation stage, Mr. Takeuchi had just gotten back from seeing the new Ghost Rider movie and wouldn't stop going on about how awesome it would be if Saber's motorcycle could transform too, but, uh… honestly it seemed like it would be a lot of trouble. I was really glad I managed to get out of writing that one!