Timing is everything. And unfortunately for the 2015 Audi RS5, my test car was delivered just one week after I spent a glorious, sun-splashed weekend squiring a BMW M4 convertible around the North Fork of Long Island.

The M4 is a simply stupendous car: precise, powerful, and utterly exciting. It's good at everything a sports car should be good at.

It cannot bore you. And you can put the top down. What spirit! What style! It thrilled my 4-year-old — not to mention my inner 4-year-old — to no end.

On paper, the RS5 is actually the more impressive two-door. Its 4.2-liter V8 churns out 450 horsepower, versus 425 from the M4's inline 3.0-liter twin-turbocharged inline 6. And the RS5 can be had with boffo options for less than $80,000. (And there's a convertible available; I had the coupe). Meanwhile, the loaded M4 I tested tipped the price scales at $96,000.

The RS5 also looks great, with a kind of broad, sleekly shaped and muscled stance that bulges nowhere. My shimmering white car gave the impression that it had been painted by Under Armour. The grille is big, bold, and black, but the Audi badge sits in neat proportion to the angular headlights. The interior is sporty, yet comfortable — Audi has the best interiors in the business — and the infotainment system is a pleasure to use. (BMW's continues, after years of derision, to be deeply not good.)

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It should all add up to reliable thrills. I mean, zero to 60 in 4.5 seconds? Go ahead — rock your need for speed! It even had a cool little spoiler in back that can be electronically activated at the push of a button. And a flat-bottom steering wheel! Serious sporty racing touches.

Unfortunately, I just didn't want to rock a need for speed. I tried. On a magnificent Saturday, I zipped around and waited for something soulful to happen. That juicy V8 should have obliged.

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But the power was ... just ... kind of ... there. At some level, it felt like a Buick. The sound was adequate and satisfying, but hardly a full-throated yowl. In "dynamic" driving mode, the RS5 felt alarmingly docile.

I'll tell you all about the M4 in a future review, but let's just say it suffered from none of these complaints.

But then something happened.

Sunday arrived, and with it a thunderstorm.

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And suddenly the RS5 was a new car.

I would not have wanted to be managing the M4 and its rear-wheel-drive awesomeness in a downpour. But the RS5, with its quattro all-wheel-drive system and impeccable seven-speed automatic transmission, came into its own in the watery slop. This is the most surefooted powerful car I've ever driven. Normally, I get nervous with a high-horsepower, performance-tuned machine when the weather is rotten.

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