The 1991 Ford Sierra last failed its MOT on 30 May 2007 at 28,585 miles, and no subsequent test record exists. That is a gap of nearly nineteen years without a valid certificate. The single recorded defect was severe: the nearside rear vehicle structure had excessive corrosion within 30 centimetres of the body mountings, seriously affecting its strength. That is a primary load-bearing area on a monocoque shell, and the tester judged it a direct failure rather than an advisory. No later retest result is available, so the corrosion may have been repaired, or the car may have been off the road ever since. Either way, the maintenance trend is unknown after 2007, and the vehicle cannot be considered roadworthy on paper.
The mileage pattern is unusual. Between 6 May 2006 at 22,331 miles and 30 May 2007 at 28,585 miles, the car covered 6,254 miles in roughly one year. That is a sharp jump compared with the long-term average of about 817 miles per year across its life. After May 2007 there is no further recorded mileage, so it is unclear whether the car was driven, stored, or broken up. A sudden late-life increase in use can point to a change of ownership or a final period of heavier driving, but without later MOT entries the pattern remains incomplete.
A buyer should treat the 2007 structural failure as the central concern. The nearside rear floor, sill, or subframe mounting area must be inspected for original rust, previous welding, or poorly executed patches. On a 1991 Sierra, rear chassis legs, jacking points, and suspension mounting points are common corrosion traps. Even if a repair plate is present, the quality of the weld and the surrounding metal thickness need checking with a probe or a professional inspection. Surface rust on a thirty-five-year-old car is expected, but any softness or movement around the rear mountings would still be a fail.
Beyond the known structural issue, the lack of recent MOT data means other systems are unverified. Rear brake lines, handbrake linkage, and flexible hoses can deteriorate during long standing. Suspension bushes, coil springs, and shock absorbers may have aged rather than worn. Tyres with old date codes, perished fuel pipes, and degraded rubber hoses are likely if the car has sat. A compression test, underbody inspection, and brake function check are advisable before any purchase.