Car Spy Jim Dunne Catches a Revised 2015 Ford Mustang

To IRS or not to add IRS, that is the Mustang question, and not for the first time in the pony car’s life.

Jim Dunne caught the 2015 model year Ford Mustang, which he opines will have an independent rear suspension along with freshened sheet metal. At least that’s the impression he got from viewing the rear of a Mustang test vehicle, location unspecified. Taillights, upper panels and the license plate mount are the same as current Mustangs on the prototype, so why cut out the lowest panel?

Well, there could be many reasons, depending on what’s going on underneath, and you can’t tell that from the photo. However, it does look as if the traditional solid rear axle and differential are not there. Media speculation has it that the Mustang will upgrade to an independent suspension, so Dunne might be projecting based on those reports. The sales success of the Camaro with its independent rear suspension – 78,554 versus 77,458 for the original pony car from the Blue Oval year-to-date – argues for a Ford change, which has run prototype IRS  ‘Stangs before, but never put them into production.

More to the point, perhaps, Lincoln needs an answer to the Cadillac ATS compact, so planned coupe and sedan versions will need an IRS to be credible. This, ironically, is a revisit of the original plan for the Mustang, Thunderbird, Australian Falcon and the Lincoln LS and Jaguar S-Type that were launched together in 1999. Ford was supposed to consolidate all the platforms going forward based on the competent shared S and LS platform, but never did because of internal politics, executive bickering, national chauvinism and, well, stupidity.  

Front view of the next Ford Mustang due in early 2014.

IRS offers some ride and handling advantages over solid axle layouts – a more refined ride, less axle tramp and better traction on smooth and rough pavement. However, the higher costs involved in the complicated independent designs with a rear sub-frame, multiple locating arms, coil springs and sophisticated bushings, as well as the additional weight incurred have been the disadvantages that stopped its use at Ford. Indeed, the current Camaro is about 300 pounds heavier than the Mustang, about half of which is the rear suspension.