Fun to drive became the only three words that mattered for Lexus International chief engineer Junichi Furuyama when he was asked to create a more aggressive IS sport sedan.That was three years ago, and since then, he and his team have been focused on their simple mission: Whatever they did had to make the IS fun to drive, or it was out.To bring their mantra to life, they did things that made line accountants weep blood.Instead of standard welding, Furuyama and his team used 82 feet of body adhesive, which is a lot for a 15-foot-long car.They laser-brazed the body to the roof (or the roof to the body, depending on your perspective), eliminating that unsightly roof-drip molding that none of us ever noticed anyway.They borrowed cockpit design cues and tech from the companys bazillion-dollar LFA supercar.They re-engineered the front double-wishbone suspension and borrowed the rear suspension from the new GS.They installed a super-smart eight-speed direct shift transmission (in the 350 RWD) and ad infinitum.So did all that effort pay off? Heres what Furuyama said after one particularly grueling test circuit near the projects end: When I depressed the accelerator or turned the steering wheel, the IS responded as though provoking me by saying, You can depress the accelerator further. You can turn the steering wheel further. Go ahead. I can take it.Since its his baby, youd expect him to wax poetic. But heres what youre likely to say after a vigorous test drive: Boy howdy, I need one of these right now!Personality abounds in both versions of the IS. The 250 IS delivers 204 hp and 184 lb-ft of torque, which is plenty for the average city commuter. The peppier 350 IS packs 306 hp and 277 lb-ft of torque: Guess which one we preferred?In either version, Furuyama and his peeps thought this thing through, because the driving experience is fun as hell.All that adhesive glues the IS to the road, because even in tight curves, handling and balance are composed and assured. Theres no heaviness or hesitation, and the new electric steering system delivers plenty of driver feedback.Fit and finish from every angle is appropriately Lexus-like, which is to say, superb.Opt for the F Sports package option and youll get the giant black-mesh Darth Vader grille, the excellent NuLuxe faux leather interior, twin projector LED headlamps, heated sports seats, perforated leather steering wheel and adaptive variable suspension.The 8-inch color liquid-crystal display gauge, borrowed from the LFA, sparked an acid-flashback moment Hey, did that thing just crawl across the dash? But, like the center stacks round analog clock, it lights up real pretty at night. All the requisite technology youd expect is easily accessible via the 7-inch tabletlike display, and the optional nav system and Lexus Enform App Suite lets you make dinner and theater reservations as easily as adjusting the Jetson-like electrostatic touch-based temperature controls.Its roomier, too: nearly an inch up front and just over an inch-and-a-half in back, aided by sculpted front seatbacks.Need to bring your skis? No problem: The back seats flatten forward. Car and Driver magazine liked the IS 350 F Sport so well, it chose it over the BMW 335i and the Cadillac ATS 3.6. Thats saying something.Put simply, the entire 2014 Lexus IS line is all about personality: bold new looks, enhanced cabin amenities and revised engineering for a dramatically new driving experience.Lets give Furayama-san the final word: Just take it for a drive. Then you will understand.Freelance writer Brian Melton has a well-documentedneed for speed.