[4] Due to financial limitations the decision was made to keep the front-engine, rear-wheel-drive layout of its predecessor, and pursue improved fuel economy through advanced aerodynamics.

[5] The Probe III design study unveiled at the 1981 Frankfurt Motor Show foreshadowed the direction Ford would take with the Sierra.

[note 1][7] Lutz spearheaded the plan to bring a version of the XR4i to North America to compete with sporty luxury imports like BMW.

The 'Sierra' name was not used in North America, since it was already used by General Motors for their GMC C/K Sierra pickup truck, and sounded too similar to the Oldsmobile Cutlass Ciera.

Using body panels from Ford's factory in Genk, the cars were largely hand-built by Wilhelm Karmann GmbH in Rheine, Germany.

[13] The XR4Ti kept the 3-door semi-notchback hatchback body style of the XR4i, including the European version's triple side-window profile and bi-plane rear spoiler.

[16] Altogether 850 unique parts were developed for the car destined for the US and Canada, and these changes added approximately 280 lb (127.0 kg) to the weight.

The front suspension comprised Macpherson struts with concentric coil springs and lower lateral links triangulated by an anti-roll bar.

The rear suspension used semi-trailing arms with coil springs ahead of the axle half-shafts, and shock absorbers behind.

Spring rates were softened compared to the XR4i, based on feedback from Jackie Stewart, who had been brought in as both a development tester and spokesman for the car.

Engines in cars equipped with automatic transmissions had maximum boost set to 8 to 10 psi (0.55 to 0.69 bar) and produced 145 hp (108 kW).

In cars with manual transmissions maximum boost was raised to 12 to 14 psi (0.83 to 0.97 bar) and the ECU programming was modified to allow the engine to produce 175 hp (130 kW).

The second-order vibrations produced by this large four cylinder engine had been noticeable when it was used in the turbocharged Thunderbird and Cougar models.

To minimize these in the XR4Ti without resorting to extreme measures such as adding balance shafts, extensive work was done to reduce noise, vibration, and harshness (NVH) in the power-train.

The second measure was to reduce the amount of vibration transmitted to the body structure by using soft rubber engine mounts.

One such special, called the Scorch XS and built by Ralph Todd, replaced the Ford engine with a twin-turbocharged Nissan VG30DETT V6.

In their test data they stated the press car came with a limited slip differential, something that was not offered as standard or an option for the XR4Ti during its production.

The first test car returned a combined city/highway fuel economy of 24 mpg‑US (9.8 L/100 km), and generated 0.80 Gs of lateral acceleration.

[32][33] Despite the XR4Ti never being sold outside of the United States and Canada, Andy Rouse campaigned one in the British Saloon Car Championship.

Between 1986 and 1987, Pete Halsmer and Scott Pruett campaigned the Roush-prepped XR4Ti, although of a tubeframe construction like that of a silhouette racing car, to take the Trans-Am Series title.