Stretch Limousine Product

Overview

A stretch limousine is a series-production sedan or SUV that a second-stage coachbuilder cuts in half behind the B-pillar and lengthens with a welded structural insert, usually between 70 and 180 inches. The donor manufacturer ships the car as an "incomplete vehicle"; the coachbuilder finishes it under multi-stage manufacturer rules and certifies the result against the applicable FMVSS items at the new gross weight. Ford's Qualified Vehicle Modifier (QVM) and GM's Cadillac Master Coachbuilder (CMC) programs publish stretch limits, frame splice locations, and electrical tie-in points so the finished car keeps its powertrain warranty.

The defining engineering problem is restoring stiffness. Cutting a unibody car in the middle removes the structure that carries bending and torsion between the axles, and the insert must put it back over a wheelbase roughly doubled to about 6.1 m. The Stretch Section does this with boxed Frame Insert Rail members spliced into the donor rails, deep Rocker Reinforcement beams along each sill, a new Floor Pan, and a leaded-in Roof Panel, skinned with Sheet Metal Panel sides and fixed Fixed Side Window glass. The rockers do most of the work: on a stretched car the sill section is the main beam, which is why program rules forbid cutting door openings into the insert beyond the approved pattern.

Donor platform and driveline

The Donor Vehicle Platform is left as close to stock as possible. The V8 Engine and Automatic Transmission are unmodified apart from a shift-calibration re-flash for the roughly 1,500 kg of added curb weight, and the Driver Cockpit gains only partition and cabin-control switches on the Dashboard.

Bridging the long wheelbase falls to the Extended Driveline. A single propshaft of this length would whirl below highway speed, so the torque path is split into three Driveshaft Segment tubes, each kept under about 1.5 m, supported at the joints by rubber-isolated Center Support Bearing hangers bolted to insert crossmembers. Brake, fuel, and electrical runs are lengthened with the Extended Brake Line Kit routed along the frame rails. At the back, a Heavy-Duty Rear Axle uprated for the ~4,500 kg GVWR replaces or supplements the donor unit.

The chassis is rebalanced by the Suspension and Brake Upgrade: stiffer front Coil Spring units, four Heavy-Duty Damper units, and self-leveling rear Rear Air Spring bags whose compressor holds ride height whether the car carries one passenger or ten — each bag monitored by a Pressure Sensor. The Heavy-Duty Brake Kit restores stopping distances at the higher gross weight.

Partition and cabin

The Chauffeur Partition separates chauffeur from passengers with a steel Partition Frame tied into roof bows and floor, carrying a tempered Partition Glass panel. The Glass Lift Mechanism raises and lowers the glass in about four seconds using a Servo Motor and Helical Gear Pair driving cable carriers in twin Lift Guide Track channels. Because the raised glass blocks normal speech, a duplex Intercom System with flush headliner Intercom Microphone capsules and Speaker outputs links the two compartments.

The Rear Cabin Interior is built around the J-Seat Bench, a continuous side- and rear-facing bench on a steel-reinforced Seat Frame with multi-density Seat Foam and a sewn Leather Upholstery. Every designated position gets a lap belt from the Seat Belt Set anchored through the frame to the floor structure — side-facing seats are exempt from three-point requirements but not from belt anchorage loads. Opposite the bench, the Bar Console carries drained stainless Ice Well bins, a road-proof Glassware Rack, and a spring-retained Decanter Set on a veneered Console Cabinet.

Climate, power, and entertainment

The donor HVAC system was sized for a five-seat sedan, so the Secondary HVAC System adds a rear Rear Evaporator Unit of roughly 7 kW teed into the engine compressor circuit through an extended Refrigerant Line Set set, with twin Blower Motor fans, an electric Heating Element booster, and a HVAC Duct Set feeding ceiling vents down the cabin. Passengers set the rear zone on the Rear Climate Controller.

All of this roughly doubles the car's electrical load, so the Coach Electrical System fits a second 220 A Auxiliary Alternator, an auxiliary 12 V Battery, and a dedicated Coach Fuse Panel so that a fault in a coach circuit cannot take down the donor harness. Cabin loads switch through Relay banks fed by heavy Wire Bundle runs along the rockers.

The Entertainment and Lighting System provides multi-zone audio through eight Speaker positions driven by the ~800 W class-D Audio Amplifier, video on two LCD Panel displays, and a Touch Digitizer control panel at the bar. Accent lighting — addressable RGB LED Strip runs, bar glow, and the Fiber-Optic Star Harness star ceiling — is sequenced by the LED Lighting Controller.

Operating context

Stretch limousines are livery vehicles: chauffeur-driven, speed-limited in many fleets, and inspected under state limousine regulations that govern seating capacity, emergency exits, and belt counts. A 120-inch sedan stretch typically seats eight to ten, turns in about 16 m, and spends its service life on airport and event runs of under an hour, which is why cabin amenities — bar, lighting, intercom — get more engineering attention than outright road performance.