The 2009 Mini Cooper is the automotive equivalent of a boundlessly energetic Jack Russell terrier. Sure, it makes a lot of noise. Sure, it plays a little rough sometimes. And, well, it's little. But when that pooch is bounding toward you, yipping gaily, lips peeled back in an apparent smile, you can't help but smile back. That's the Mini in a nutshell -- it's not the most refined pup in the litter, but its exuberant personality is bound to win you over.

Let's start with the Cooper's retro-cute mug, which evokes the original Minis of many decades ago. It's retro done right, in our collective opinion, providing just enough old-school charm without going over the top. Remember those old Dodge Neon ads that ended with the car saying "Hi"? The Cooper says "Hi" too, but with a mischievous grin that attracts stylistic trendsetters and automotive enthusiasts in equal numbers.

The Mini also manages to please a wide variety of drivers, thanks to its discrete trim levels. A relatively demure runabout in base trim, albeit a dynamically well-sorted one, the Cooper is perfectly content playing grocery-getter or errand-runner. Step up to the turbocharged S or new John Cooper Works model, however, and the Mini is transformed into a hot hatch with sports-carlike acceleration and handling. In any trim, owners are treated to amazing fuel economy -- up to 32 combined mpg for the base model and 29 combined mpg for both the S and John Cooper Works.

For 2009, the Cooper Convertible is now based on the same all-new Mini body style introduced two years ago. Aside from gaining attributes inherent with the latest Mini -- new engines, a higher-quality cabin, more comfortable seating and fussy interior controls -- the convertible gains a few specific improvements. Pop-up roll bars replace the former fixed units that eliminated any semblance of rear visibility -- now there's a fleeting semblance. The tiny trunk gains an expandable opening feature, while a new gauge, known as the Openometer, keeps track of how much time you spend with the top down? Why would you need this? You don't, but Mini likes doing funny stuff like that.

As noted, the 2009 Mini Cooper isn't the most luxurious hatchback or convertible out there. If muted road noise, a usable backseat and a compliant ride are on your wish list, the Volvo C30, VW GTI or VW Rabbit might make a better choice. If those issues, plus rear visibility are important in your convertible, a VW Eos is better, but pricier. The Mazda Miata is also worth consideration. But we can't think of another car on the road that comes close to the Cooper's cocktail of style, fuel efficiency and fun.

The 2009 Mini Cooper is available in hatchback and convertible body styles. Each is available in three trim levels: Cooper, Cooper S and John Cooper Works.

The base Cooper comes standard with 15-inch alloy wheels, a selectable Sport setting for steering and throttle response, full power accessories, air-conditioning, leatherette (premium vinyl) upholstery, a tilt/telescoping leather-wrapped steering wheel, a trip computer and a six-speaker stereo with a CD player and an auxiliary audio jack. The convertible adds a fully powered soft top with a sliding "sunroof" feature and remote control, bottom-hinged and expandable trunk opening, a climate control top-down setting and the "Openometer" gauge that times how much time is spent with the roof lowered. The Cooper S adds a turbocharged engine, 16-inch wheels, firmer suspension tuning and sport seats (optional on the base Cooper). The John Cooper Works includes a more powerful turbocharged engine, 17-inch wheels, upgraded brakes with Brembo calipers and unique exterior and interior styling cues. A limited-slip differential can be fitted to both the S and the John Cooper Works, as can an even stiffer sport suspension for those who plan on taking their Mini to the track.

The options list is anything but mini, thanks to parent company BMW, which has passed along its philosophy of allowing consumers to customize their cars. Choices include different wheel designs, a panoramic dual-pane sunroof, xenon headlights, cruise control, rear park assist, front and/or rear foglamps, automatic climate control, leather and/or cloth upholstery, multiple interior color schemes, heated seats, heated power-folding mirrors, a multifunction steering wheel, Bluetooth, rain-sensing wipers, keyless ignition/entry, an auto-dimming rearview mirror, an integrated navigation system, a portable navigation system, HD radio, satellite radio, iPod connectivity and a variety of dealer-installed features. An upgraded 10-speaker audio system is also available -- and strongly recommended, especially for the convertible.

The base Mini Cooper comes with a 1.6-liter four-cylinder that produces 118 horsepower and 114 pound-feet of torque. The Cooper S hatchback features a turbocharged version of the same engine that produces 172 hp and 177 lb-ft of torque (192 lb-ft at full throttle, thanks to an "overboost" function). The John Cooper Works is equipped with a revised version of this turbocharged motor that pumps out 208 hp and 192 lb-ft of torque (206 lb-ft via overboost). All three come standard with a six-speed manual that includes hill-start assist, while a six-speed automatic with manual shift paddles is optional on the base and S models.

In performance testing, we've clocked a Cooper S at 6.5 seconds from zero to 60 mph. As for the base coupe, Mini claims it'll do the 0-60 drill in 8.5 seconds -- not too shabby given its remarkable fuel economy of 28 mpg city/37 mpg highway and 32 mpg combined with the manual transmission. The Cooper S and John Cooper Works are both rated at 26/34/29 mpg with the stick shift, which is perhaps even more impressive than the base model's ratings given their grin-inducing performance. The automatic drops fuel economy by 2-3 mpg.

All 2009 Mini Coopers come standard with antilock disc brakes, stability control and front-seat side airbags. Side curtain airbags are standard on the hatchback, while the convertible features pop-up rollover bars and larger front side airbags that extend to head height. Traction control is optional. In government crash testing, the Cooper hatchback achieved four out of five stars for frontal crash protection. Side-impact tests resulted in a perfect five stars for front side protection and four stars for rear occupants. In Insurance Institute for Highway Safety testing, the Cooper hatchback achieved the best rating of "Good" for frontal-offset crash protection and the second-best rating of "Acceptable" for side impact protection.

The 2009 Mini Cooper is an amusement park ride on wheels, albeit a noisy one. Even the base model can hold its own when the going gets twisty. It rides stiffly, however, and the Cooper S is stiffer still, so we'd pass on the hard-core sport suspension and bigger wheels option unless you need the extra performance for track days.

The base Cooper is peppy enough for most drivers, but the turbocharged variants pile on the speed and cornering G-forces like go-karts on steroids. Notably, these turbocharged engines are already pulling hard at 2,000 rpm, though some drivers complain about distracting amounts of torque steer. In terms of outright speed, the John Cooper Works model is the swiftest, but the Cooper S is close enough that it should suffice for all but the most ardent Miniphiles. The standard manual transmission is one of the easiest gearboxes to master, with snick-snick shifts and a light and compliant clutch. The automatic isn't the smoothest-shifting in the world, but in manual mode, it responds quickly to the driver's paddle-shifted inputs.

The 2009 Mini Cooper's interior layout is as head-scratching as the exterior is endearing. The pie-plate-sized, center-mounted speedometer is kitschy (think Flavor Flav's clock necklace) and largely useless. The climate controls aren't finger-friendly, even after familiarization. Meanwhile, the volume control for the stereo is stranded alone in the middle of the center stack, and what looks like the volume knob is actually a redundant tuning/track-skip knob.

On the bright side, the diminutive Mini is impressively accommodating, even for taller drivers -- neither headroom nor legroom is an issue. The rear seat, however, is another matter, with nearly nonexistent legroom. Trunk space behind the rear seat is severely limited, but folding down the 50/50-split rear seat creates a useful square-shaped cargo area. The convertible features a tailgate-style trunk opening with an upper portion that lifts up to allow larger items to fit in the tiny 6-cubic-foot trunk. The 50/50-split rear seat folds down to expand space into the cabin. Unlike the old Mini Convertible, it is possible to see out the back of the car with the top lowered thanks to redesigned rollover hoops -- but you don't see much. With the top raised, rearward visibility is very poor.