Base 4dr Rear-Wheel Drive Sedan
2014 BMW M5 Review

The last time the Dinan name graced the pages of Autoblog, Michael Harley was waxing poetic about the S3-R BMW 1M Coupe, a car that still stands in his ranks as one of the best cars he's ever driven. And that wasn't just because it was, you know, amazing. It's because as far as tuners go, Dinan produces some seriously well-executed products. Harley said of the 1M, for example, "It was so fully formed and well-rounded that it felt like BMW itself had made it."

Eager to sample some of these wholly wonderful wares, I cleared a few hours in my Monterey Car Week schedule and booked a date with the S1 M5 you see here – the (current) daily driver of Mr. Steve Dinan, himself. But unlike the S3-R 1M the company tuned previously, the donor car in question here is vastly different and, if I'm honest, not as good. See, I adore the stock 1M in a way words cannot express, but the standard-issue M5... good as it is, there are indeed a few flaws.

But after driving the Dinan S1 M5 around the Monterey Peninsula, I can confirm two things. First, Harley's conclusion that Dinan builds products that feel 100 percent BMW-spec is absolutely true. And second, Steve and the gang haven't just created a tuned M5, they've built a better one.

Driving Notes

• Power is definitely a huge part of the Dinan M5 story, but trust me, the numbers don't tell the whole tale. Thanks to a carbon fiber cold air intake, free-flow exhaust system and the Dinantronics Performance Tuner that alters the car's ECU, output has been boosted to 675 horsepower and 644 pound-feet of torque – increases of 115 hp and 144 lb-ft over the standard M5. That horsepower number is even a full 100 greater than the Competition Pack-equipped sedan.
• The following statement should come as no shock, then: this thing is quick. And while Dinan doesn't provide specific 0-60 numbers, my seat-of-the-pants feeling is that it's somewhere in the high-three-second range – definitely quicker than the 4.1-second 0-60 sprint of the standard M5. It's a fast beast, too – the top speed is electronically limited to 190 miles per hour.
• This specific car was fitted with BMW's seven-speed M-DCT dual-clutch 'box, firing off incredibly quick shifts via the steering wheel-mounted paddles. If you're keen on rowing your own, the S1 kit is available for cars equipped with the six-speed manual transmission, as well.
• Like I said, this M5 isn't just about sheer oomph. Underneath that big, four-door body are a host of chassis upgrades, including negative camber front control arms, lightweight tubular anti-roll bars, and Dinan's specially developed adjustable coilover system – something that actually gives the car a lowered, more aggressive stance while decreasing body roll.
• The Dinan M5 is lighter, too – 4,300 pounds, versus the stock M5's curb weight of 4,390. And that lighter feeling is immediately noticeable the first time you enter a corner. The lowered ride height and more robust suspension setup allow the car to stay flat as a pancake through curves, and minimizes instances of both understeer and oversteer when really pushing.
• Of course, with a lowered ride height, one would normally expect a harsher ride quality, but that isn't the case here. You could really drive this thing every single day without issue, and during the start and end of my drive route in downtown Monterey, bumps and blemishes were easily managed by the S1 M5. It's still plenty comfortable, like a big BMW should be. But do note, that lower stance can prove problematic on steep driveways or sudden changes in road elevation (yes, I scraped it – sorry, again, Mr. Dinan).
• Once out of Monterey and on roads more apt for spirited driving, I would run the M5 hot through a bend, and Steve riding shotgun would tell me the car could handle even more than I was willing to give it on public pavement. Of course, the incredibly sticky 285/30ZR20 Michelin Pilot SuperSport tires helped here, offering tremendous amounts of grip; I didn't even come close to finding their limits.
• The standard M5 steering is fine here, offering plenty of feedback through the leather-wrapped wheel, and it's through the helm where you really sense the car's more agile demeanor. Where a normal M5 can feel piggish and heavy in corners, the Dinan-tuned example feels way more nimble. BMW's stock carbon ceramic brakes work wonders, too, halting all that force with ease.
• A final bit of praise goes to the tuned exhaust, which gives the M5 more aural delight. Additionally, the revised underhood bits allow the overall engine sound to be improved (though the M5's active sound enhancer is still doing its job, too), with pronounced turbo whine – you can certainly hear a big difference, even at low speed.
• The cabin remains stock, as does the rest of the exterior. Dinan does offer upgrades like aluminum pedals, carbon mirror caps, carbon fiber rear spoiler, a decklid badge and a serial number plaque, too.

Of course, all of this comes at a cost – $13,487 on top of the $93,600 M5 donor car. But consider this: the M5's Competition Package will set you back $7,300, so for the extra $6,187 of the Dinan S1 tune, you're getting a full 100 more horsepower on top of the already increased output, a better suspension setup, and a car that's seriously better to drive. Plus, all of Dinan's work is backed up by the same four-year/50,000-mile warranty offered by BMW, and you're getting something rather unique. Besides, I have to imagine that if you're already willing to spend over $100,000 for an M5, a few extra thousand bucks isn't going to break you (says the man in the much lower tax bracket, of course). Got an M6? The same S1 kit is available for that car, too.

I'll revert back to Harley's thoughts here, and say that the best part of the Dinan experience is how well-rounded the whole thing feels – the car doesn't feel all tuner-y like, say, a Roush Mustang. With the Dinan S1, you're not just getting a hotted-up M5 with bolt-on bits. You're getting a bona-fide supersedan with better chops than BMW itself can provide.