I drive tuner cars all too often I consider "different than stock" rather than better. With as good as modern cars are from the factory, it's becoming more and more challenging to make real improvements. Dinan Performance has been in the business of tuning BMWs for 36 years. Its M.O. is to take the Ultimate Driving Machine to whatever level exists above that absolute level of marketing speak. What's separated Dinan cars from most of the industry throughout the years is the holistic approach to tuning that focuses on the car's performance, rather than just components. While Dinan will happily sell you a piece at a time, you're doing yourself and your car a real disservice by not just waiting and doing it all at once. Who wants to walk into an amazing restaurant and leave after the appetizer?
For whatever reason, the first thing people always want to talk about with any tuned car is the engine. The first time I drove an S55-powered F8X, my initial feeling was that the last thing it needed was more power. As already mentioned, the twin-turbo six starts out-muscling the old V-8, nearly off idle. There is so much torque, the stock car has trouble getting it to the ground. That didn't stop Dinan's engineers from finding more boost. ECUs have been giving tuners headaches for years, but the last few generations have produced full scalp-splitting migraines. To circumvent the problem, Dinan has begun employing an intercept or piggyback system that operates in between the car's sensors and the ECU. Signals from the car's factory sensors are intercepted, changed slightly, and then sent to the ECU. As an example, a sensor might be registering 12 psi of boost in the manifold. The computer takes that signal, adapts it down to look like 8 psi, and sends that to the ECU. Thinking that it is only getting 8 psi, the ECU holds the wastegate and diverter valve closed to get what it thinks is the requested 12 psi. This type of tuning has been around for years with varying degrees of success; we may be looking at some of the best yet.
The car you see here is equipped with Dinan's Stage 2 system, which is tuned to work with the freer-flowing cold-air induction system (CAI) and axle-back exhaust. The CAI kit is said to add as much as 14 hp and uses carbon-fiber airboxes and an intake crossover tube, plus larger MAF sensors and 30 percent larger cylindrical air filters. The exhaust keeps the factory butterfly valves in the system, so in normal mode, the M4 is nearly factory quiet. But hit the Sport button and the valves allow the flow to bypass the muffler for reduced backpressure and maximum sound. The Dinantronics Tuner, intake, and exhaust all work together to bring the M4 up to a ridiculous 530 hp and 504 lb-ft of torque.
As I already mentioned, the M4 rolls out of the factory feeling overpowered. If you are going to piecemeal one of these together, I would start with the chassis modifications. To start, Dinan replaces both the rear toe-links and the forward lower trailing links in the rear suspension with tubular aluminum pieces that use Teflon-lined spherical bearings instead of rubber bushings. The stock pieces deflect under load and cause the rear end of the car to wander. These pieces keep alignment settings exactly where they're set by eliminating the bushing deflection.
Next up, whether the car is equipped with fixed damping or BMW's electronic damping control, Dinan has a coilover kit that keeps the factory shocks but replaces the fixed position springs. Threaded sleeves fit over the factory shocks, allowing for as much as a 1-inch drop in front and 1.5-inch drop at the rear. Dinan recommends no more than a half-inch drop at either end to maintain enough suspension travel for optimum handling and ride while also not compromising suspension geometry. The included springs are 50 percent stiffer in front and 10 percent stiffer in the rear. Helping out with greater roll resistance are front and rear antiroll bars. Both are adjustable, with the front being variable from 57-103 percent stiffer than stock and the rear being 0-13 percent stiffer than stock. Those of you familiar with suspension setup have probably noticed Dinan feels the front needs to be significantly stiffer while stock rear rates are nearly ideal. Clearly, getting power to the ground is a major priority with this setup.
What is in my opinion one of the best upgrades to the car is the wheel and tire package. The wheels are 20x9.5 inches in front and 20x10.5 inches in back. Even at this gargantuan size, the forged 6061-T6 aluminum wheels are 22 and 23 pounds, respectively. Dinan could have fit 21- or even 22-inch wheels under the car, but at that point, handling would have suffered. The test car was fitted with Pirelli P-Zero Corsa tires in a 275/30-20 front and an amazing 305/30-20 in back. Yes, the front tire is now wider than the factory rear. These tires are also slightly taller than the factory tire, meaning the car hasn't lost as much sidewall as it normally would with a plus-sized wheel fitment. As we've been seeing lately, car manufacturers and the best performance tuners are starting to back away from the ridiculously small sidewall sizes.
How does all this work on the road? In a word, better. The Dinan M4 is better in every way from the stock car. I'm not talking in terms of numbers, either. I didn't have a stock M4 to drive back to back with this car, so I don't want to say that it feels way faster. I'm sure it probably is, but the stock car is so fast, I don't think it's realistic to make those claims without driving them back to back—or even better yet, with test equipment.
I can tell you that it handles better, both subjectively and objectively. The amount of grip available is something you would have needed a race car to achieve not that long ago. The amount of rubber under this car is one thing, but the balance of the suspension and the ability to soak up bumps are different things altogether. It commits to turns with a ferociousness few cars can match. I hear the complaint all the time that new cars feel big and heavy—well, they are. This F82 is roughly the size of an e63 M6 or even an e39 M5. Although it feels every bit as big as those two cars, it will utterly destroy them on the road and instills far more confidence doing it. It isn't saying much that it's better than the M6, but it is a pretty big proclamation to say that this is probably more fun than the legendary e39 M5. Again, I would need to drive them back to back to make a definitive statement.
This is without a doubt the best thing I've driven with a roundel that's been built in the last five years. The Dinan M4 is just so easy yet still so rewarding to drive. It's challenging to drive no doubt, but it isn't going to punish you as a driver until you master it.
But what about the knit back driving glove and silk scarf experience? I never liked the sound of the s65 V-8; I thought it was unrefined and loud for the sake of being loud. This car growls and roars without all the desperate pleas for attention. There is some lag, but there is so much torque available so quickly that waiting that split second for the turbo to spin up rewards with twice the torque of the naturally aspirated counterpart. I know purists will also complain about the lack of a manual transmission, but I don't miss it in this car. The e46 is the last M3/4 that I would want with three pedals, and that's only because the SMG was so horrible. If you really think you need a lightweight, manual transmission, naturally aspirated M3—the e36 is an amazing value right now and I would suggest you buy one of those.
So what makes the Dinan M4 so good? Some of it is just staying away from the old tuning tropes. It is barely lower than stock, which means it still has plenty of suspension travel to do what suspension is designed to do. It still has a decent amount of sidewall on the tire. Sure, those super-low-profile tires stretched out on the wheel look great, but they aren't that great for handling. The engine isn't over-stressed. There is nothing worse than a turbocharged engine that's surging, constantly at the edge of its efficiency or continually pulling to prevent detonation. This car pulls as smooth as stock, and most people would never know the difference.
Yes, you can probably build this car for less money by selecting other aftermarket components. You can probably squeeze a bit more power from the engine and extract a few more tenths of a G-force if you really tried. Dinan, however, offers a supplemental warranty to back up the factory warranty, which is peace of mind I would find tough to pass up. This car isn't for the guy who wants everyone at the car show to know he has a tuned car. Dinan builds cars for people who actually drive cars. Is it different than the factory car? Yes. More importantly, it's better.