For Sale: 1984 Lotus M90 Prototype

1984 Lotus M90 Prototype

A Texas-based member of the community has reached out to us to offer his right-hand-drive 1984 Lotus M90 Prototype for sale here in Australia. Read on for the full details on this fascinating piece of Lotus history.

Thanks to Tom Smith. For further details, or to ask any questions, please contact him via email.

The car is listed with Hemmings, and you can get to the listing by clicking this link.

1984 Lotus M90 Prototype

1984 Lotus M90 Prototype For Sale

This 1984 Lotus M90/X100 is the only one produced in this color combination, and the only one with a manual transmission. In fact it’s the only one Lotus ever made.

Lotus designed and built the M90/X100 intending it to be the replacement for the Elan. Even though only one was produced, it was built using full body molds and everything was done assuming it would go into full scale production. So things like a jack, and owner’s manual were provided. Nevertheless, there is some hard to find, but tell-tale evidence that this is a hand built prototype, such as scribe lines where the bolt holes were marked in the firewall, or the use of stainless steel for the fuel tank, which would have been carbon steel in the production model.

The M90 project stalled when company founder Colin Chapman died in 1982, as Lotus found itself in financial trouble. David Wickens of British Car Auctions ended up taking a controlling interest in the company, and the project was started up again, but renamed the X100. After redesigning the car to be a convertible, the go ahead was given in 1984 to make a single prototype. For the power plant, Lotus sourced a Toyota 4AGE drive train, as used in the 1984 Corolla GT, with a Toyota 5 speed manual transmission.

This is the last road car project designed under Colin Chapman, and is prominently featured in a newly released book, A Life in Car Design, by its Chief Designer, Oliver Winterbottom (2 full chapters with numerous photos and drawings). This unique piece of Lotus history has just undergone a frame up restoration. It is sold with a Texas title and is street registered with 1250 indicated miles. Everything works. There are a few minor flaws including small tears and stains on the convertible top, a small stain on the carpet in the driver’s footwell, and a small scratch inside the driver’s door jam. The tires have less than 50 miles, but should be replaced due to age. As can be seen in the pictures, the car is right hand drive, and has a small back seat. See below for technical specifications.

Sale includes spare parts, extensive documentation including import paperwork, bound owner’s manual, full photo documentation, and a log book detailing the restoration. See for more info. Car is in Houston, Texas.

Vehicle is available locally for pickup. Buyer is responsible for shipping if needed and payment must be received in full prior to release of vehicle to shipping carrier. When arranging shipping, note that the original windows, passenger seat, miscellaneous spares and documentation are included with the car. I will assist with arranging pickup with shipping carrier.

Title is in-hand and clear, and is being sold by an individual, not a dealer. Car is sold as-is, with no warranty.

Additional information

Powder coated frame

All interior and seat upholstery is new.

Driver and passenger door windows are light weight, bespoke polycarbonate with scratch-resistant coating as used in race cars. Electric window function is maintained. The original laminated door glass windows are included, but are severely cracked and barely hold their shape.

All lights, wipers, turn and hazard lights work

All instruments, warning lights and gauges work

Suspension is based on Lotus Excel

Stainless steel exhaust and fuel tank

Custom fit indoor car cover in fair condition.

Future stereo –There is a DIN radio cutout behind the commemorative plaque. Car is prewired for a stereo with power, speaker wire to the doors, and connection to the (working) power antenna.

Future AC – Air conditioning is not installed, but could be added as there is room for all the components and dashboard controls are existing. A new compressor (uninstalled) is included. Will need to buy/install an evaporator and housing, evaporator fan, hoses, and wiring.

Technical Specifications:

Wheelbase (at design mid laden) is 2308 mm (90.86 inches). Mid laden is half way between bump and rebound.

Suspension at mid laden:


  • Front toe in 3.2 mm
  • Camber 0.5 degree negative
  • Castor 4.0 deg
  • King Pin inclination 9.5 deg
  • King pin ground offset 48 mm
  • Anti dive 40%
  • Roll centre height 26 mm


  • Toe in 4 mm
  • Camber angle 0.5 deg
  • Anti squat 0%
  • Roll centre height 50.8 mm


  • 2.9 turns lock – lock
  • Turn circle kerb – kerb 28.5 feet
  • Ackermann 29 deg – 31 deg full lock positive

Fuel tank 12 gallons

Max engine speed 7600 rpm

Max power 123 bhp at 6600 rpm

Max torque 104.5 pounds feet (DIN) at 5200 rpm

Front track 1440 mm

Rear Track 1460 mm

Overall length 3921 mm

Width 1698 mm

Height 1187 mm

Ground clearance 130 mm (below exhaust system)

Kerb weight 895 Kg

Price: US$66,000 negotiable