“Dinan’s latest work of art, he has not only fixed a car that wasn’t broken but also sought to perfect a car that everyone considers to be as close to perfection as is humanly possible: the BMW M5”, Car and Driver wrote in 2002. Dinan had, at that point, already made a reputation for themselves as the premier BMW tuner in the United States to the point where they became offered straight from the dealer. Considering that’s just occurred for Alpina here, the endorsement of the level of engineering from the California firm was resounding. Yet that is in part because Dinan’s modifications are far from just slapping a badge and some wheels on a car and calling it done. Take, for example the M5 S2.
Dinan took what many considered to be a very highly developed 4.9 liter V8 in the S62 and went old-school to up the power; and up it a lot, he did. There was no supercharger or turbocharging here; revised intake and enlarged velocity stacks were met on the other end with tubular headers and a bespoke exhaust. Each throttle body’s bore was increased, too. These changes required a reflash of the computer, but were both lighter and more powerful. As in 76 horsepower more. That’s the best part of a 20% gain on a motor that many considered to be close to peak performance! Dinan further upgraded the suspension, brakes, wheels, and final drive, along with adding a lighter flywheel. As a result, the new S2 was, well, about 20% better than the already awesome M5. But that perfection cost, and it was more than a 20% increase. A lot more.
On top of the M5’s $73,400, if you wanted a fully spec’d out S2 you’d tack on $36,000 to the price. For that amount, you could have grabbed a nice 330Ci in addition to your standard M5! But a select few did pony up the extra cash for their extra-special E39s, and today we have a rare occasion of seeing two for sale at the same time: