All of the Cars comprised a coloured 2-piece injection-moulded nylon body with Exhausts, a nylon driver and a clear polystyrene windscreen, they had cast metal Wheels and ran on rubber Tyres. The Cars were retained in the Track slot with a Black nylon Guide Pin and picked-up the electrical current from the Track with two Collectors protruding from the underside of the Car. The 2-piece body featured a Chassis that retained all of the internal components and a Body Top which included the driver and windscreen and this fitted to the Chassis with two integrally-moulded cylindrical projecting pins as a push-fit for ease of access. The Car windscreens were produced in clear injection-moulded polystyrene and fitted to the Car bodies with three integral flat pins that were inserted into corresponding slots in the Body Top and then heat-sealed.

Wheels were produced in die-cast white metal which featured imitation wires to the outside and a hub to the inner side which provided enough width for the Wheels to be push-fitted onto the polished stainless steel Axles. The first Tyres were quite thin having raised ridges running across their width but these were superseded, in November 1962, with versions which were wider and much more realistic. These later versions featured actual treads running around the Tyre and they also had very small raised lettering ‘WRENN 152’ around both the outer and inner walls of the Front Tyres and much smaller recessed lettering around the outer wall of the Rear Tyres. There has also been seen a reference to ‘soft’ Tyres being available in the later versions.

The driver figure in the Cars comprised two individual nylon components – the driver’s helmeted head and the driver’s body, which included shoulders, arms and steering wheel. The driver’s body part had a hole in the shoulder section for the large head pin to be inserted and also two small projecting pins underneath the arms. The driver’s head featured a long pin which resembled a very long neck, and this fitted through the driver’s body section into the Body Top. These enabled the complete driver to be secured onto the Body Top through corresponding holes and then heat-sealed. Each of these driver components were moulded in a number of different colours allowing various colour combinations: White, Pale Green, Mid Green, Red & Pale Yellow. Each driver also featured some painted items with the steering wheel being painted Brown, the driver’s face and hands were painted a ‘Flesh’ colour and his goggles in a different colour.

The Collectors could be adjusted to either of two positions, corresponding to the two contact strips on either side of the slot in the track sections. This gave the facility of independently controlling up to three Cars per lane by using the two outer positions, the two inner positions or one inner and one outer. A Collector Cleaning Gauge was available to enable the Collectors to be cleaned easily and also aligned correctly to either of their required positions. The initial Collectors were manufactured from a thin piece of shaped phosphor bronze with a hole at one end to accept the short Fixing Screw into the Chassis and the copper brushes were clipped to the other end with folded tabs. When these were in their desired final position the Collectors had their Fixing Screw tightened to lock them in position. This meant that when the Cars became de-slotted the Collectors were quite vulnerable since they were rigid and needed adjusting regularly or they could become damaged easily if the Cars were not carefully returned to the slot.

In August 1963 Wrenn decided to introduce improved versions of the Collectors, which were much more successful, being short springs with the copper brushes inserted into one end. The other end of the spring was then fitted to either pin of a small steel two-pronged terminal plate which was secured to the Chassis with the same Fixing Screw as used previously for the first Collectors. The great advantage to the new design was that it was possible to change these Collectors without removing the Body Top.

The Car bodies were decorated with three number roundel transfers and having certain detail features picked out in Silver paint including the radiator openings and some of the raised details such as bonnet catches and fuel filler caps. A minor point was that the Cooper and the Ferrari bodies both had raised panel lines whilst all of the later cars featured recessed panel lines.

The axle mounts in the very first Cars were actually holes through raised semi-circular sections in the Chassis sides through which the Axles passed. This meant that the Wheels and Axles including the Ratchet Wheel on the Rear Axle had to be assembled with the Chassis. When the Cars required attention this also meant that getting access to some of the internal components was restricted. Later both the front and rear axle mountings were modified with an open section to the top and this then enabled the pre-assembled front axles or rear axles to be snapped in or out of these mountings making access easier. These different versions of the Chassis, having both solid mounts and with both open, have been seen on both colour variants of the Vibrator-motor Ferraris and Coopers but not on any of the other Cars. Since these different versions have been seen both on the Yellow Ferraris and the Blue Coopers it is assumed that these changes must have taken place at some time between September 1961 and the introduction of the Maseratis and Vanwalls in November 1962. A couple of Chassis have been seen with solid front mounts and open rears but since these are in such a minority it could well be that these were modified by their owners although there is also a possibility that these could have been modified by the factory as an interim measure and made available but it can’t be confirmed.

The Chassis featured raised lettering in three lines centred on the underside between the Guide Pin and the line of the rear axle: ‘WRENN “152” CAR NAME’ on the top line, ‘patents pending’ on the second and ‘MADE IN ENGLAND’ on the bottom line. The vibrator motor Coil Assembly featured a plated steel cover with four tabs protruding downwards. When the Coil Assembly was fitted these projected through slots in the Chassis and were folded inwards to retain the Coil Assembly. The Speed Control Lever was slid through from the inner surface of the Chassis to project out underneath the Chassis so giving access without having to open up the car body.

Wrenn decided to introduce a new motor during 1964, which they had been developing.  This new rotary motor was DC powered and was again, unlike any other motor in the marketplace. It featured three carbon motor brushes spaced equidistant around the motor which meant that one of these was positioned at the bottom of the motor and, in order to provide access to this for servicing, a small rectangular hole was necessary in the Chassis. The Chassis for all of the existing Cars needed to be modified to have this additional hole and also to have the new and larger contrate on the rear axle accommodated. This was achieved by adding a small raised curved section underneath the Chassis at the rear of the Car. These changes were initially implemented on a number of existing Vibrator-motored Chassis that were already moulded, whilst the moulding tools for these four Cars were being modified to accept the new DC motor. Versions are easily identified by this new access hole having removed part of the raised lettering beneath the Chassis and the various holes, specifically for Vibrator motor components still being present but not being used. Initially the injection moulding tools for the Maserati and the Vanwall Chassis were the first to be modified and these were launched during August 1964. The unused holes were ‘filled’ and the raised lettering was repositioned but this time it was slightly smaller and then included the lettering ‘PATENTS PENDING’ which was now in capital letters.

The new DC motor’s steel casing was used to retain the motor in the Chassis in a similar way to the Vibrator motor. This time there were just two downward facing tabs at the front of the motor casing which protruded through the front pair of existing holes and it also featured a tab at the back of the casing which slid into into the same slot that the Vibrator motor’s Speed Lever had been originally designed for. The DC motor rear axle differed to the Vibrator motor version by having a Dark Grey polystyrene contrate which then engaged onto the pinion at the rear of the DC motor. Some time later Wrenn decided to change the DC Chassis by including an additional hole centrally, at the rear of each of the cars. Although it is very similar in size to the Guide Pin hole unfortunately its use has not yet been determined after all these years. Finally the new BRM and Porsche cars were launched with this new DC motor and their Chassis incorporated all of the latest changes as mentioned above including the additional hole.

The motor chosen was called the ‘Maximiser’ and had been designed initially to power the boat in Wrenn’s Master Mariner set. It featured open copper windings around a soft-core magnet and worked off a 9-Volt supply. The motor’s Black nylon base housing featured two sections projecting below and these were inserted into two slots running across the Chassis and then heat sealed to secure. The Chassis for this version was a modification of the DC Chassis with a rectangular recess to accept the new motor and the area below the motor on the outside of the Chassis now just stated ‘WRENN MADE IN ENGLAND’ in raised lettering. As well as the main alteration of the rectangular recess in the Cars for the motor, both of them also needed minor modifications inside the Chassis and Body Tops to accommodate this new motor. The Vanwall needed to have the supports for the central/rear pin mountings (which held the two body halves together) reduced in size whilst the Maserati had to have these both totally removed to create enough space for the new motor. The Collectors, as such, were actually small pieces of standard braid as used on 1/32 scale slot cars. These were only used on the 9-Volt cars, they did not have the facility of being fitted in two positions and so independent control of two or three cars in one slot was not available. The only other differences were that the polystyrene exhausts for both cars were now just injection-moulded in a very Pale Grey, neither of the cars had any Silver painted detailing and finally the Vanwall did not have the script transfers on the Body Top. **As a point of note both Yellow and Light Green Vanwalls have been seen with this type of motor but only the Red version of the Maserati has been seen, were any Blue ones ever produced? One interesting minor point is that both of these Cars carried a different coding, being just C-codes.

This Car featured a pair of white metal exhausts which were fitted to either side of the Chassis. Each exhaust had two integral pins that were inserted into corresponding holes in the Chassis and secured by heat sealing. The Car was supplied with a pair of small Black & Yellow Ferrari badge transfers applied to either side of the Body Top. Initially these were just a Black rampant horse on a Yellow shield but later versions differed by also having a Black outline to the shield.

This Car featured a single white metal exhaust that was fitted to the side of the Chassis by two integral pins that were inserted into corresponding holes in the Chassis and secured by heat sealing.

This Car featured a single curved Silver-Grey polystyrene exhaust which was fitted to the side of the Body Top by three integral pins that were inserted into corresponding holes in the Body Top and secured by heat sealing.

This Car featured a single Silver-Grey polystyrene exhaust which was fitted to the side of the Body Top by two integral pins that were inserted into corresponding holes in the Body Top and secured by heat sealing. The Car was supplied with a pair of White ‘Vanwall’ script transfers applied to either side of the Body Top.

This Car featured two banks of four Silver-Grey polystyrene angled exhaust trumpets fitted to either side of the Car. Each of these were moulded together with a rectangular integral section at the rear which had two small pins at the rear that were inserted into a pair of corresponding holes in the Body Top and secured by heat sealing. There was also a roll-over hoop which was manufactured from thin steel rod and fitted to the Body Top through two holes behind the driver figure and secured by heat sealing.

This Car featured a single Silver-Grey polystyrene moulding at the back of the car, which included the rear part of the engine and two short exhaust stubs. The insert was fitted to the Chassis by two integral pins that were inserted into corresponding holes in the Chassis and secured by heat sealing. There was also a circular Silver-Grey polystyrene engine fan cover fitted to the Body Top and a roll-over hoop which was manufactured from thin steel rod fitting through two holes behind the driver figure and secured by heat sealing.

This code was only featured on the ‘Grand Prix’ Temporary Price List/Order Form which stated that this was a ‘Car with push start motor’. This version featured a single Pale Grey polystyrene exhaust which was fitted to the side of the Body Top by two integral pins that were inserted into corresponding holes in the Body Top and secured by heat sealing. The Car did not have a pair of White ‘Vanwall’ script transfers applied to either side of the Body Top nor was there any Silver detail painting.

This code was only featured on the ‘Grand Prix’ Temporary Price List/Order Form which stated that this was a ‘Car with push start motor’. This version featured a single Pale Grey polystyrene exhaust which was fitted to the side of the Body Top by three integral pins that were inserted into corresponding holes in the Body Top and secured by heat sealing. The Car did not have any Silver detail painting.