LAS VEGAS TO MONTEREY, California — It’s a tad ironic that BMW chose “the great State of Cah-lee-forn-ya” as Governor Schwarzenegger says, as the venue to launch its refreshed-for-2008 5 Series lineup. You see, the Golden State and BMW’s midsize saloon are both surprisingly diverse.

To showcase each with as much gusto as possible, BMW sent us on a three-day “rally” from the blasphemous streets of Las Vegas, Nevada, to the tawny shores of Monterey, California, with stops at Death Valley and Yosemite National Park along the way.

Over the “stages” (which officially began in the aptly-named blast furnace that is Death Valley), we piloted every reworked 5 Series sedan model — from the base 528i to the tarmac-torturing M5 — and took in everything, from barren deserts and snowy peaks and to towering sequoias and tony sea towns.

The ’08 5 Series showed equal diversity. While the V8 550i and the mighty V10 M5 are mechanically unchanged, the rear-driver’s base and mid-level models adopt the much-praised inline six-cylinder engines from the redone 3 Series.

The entry-level $59,900 528i (formerly the 525i) is now motivated by BMW’s lightweight alloy/magnesium 3.0-litre I-6, equipped with the automaker’s Valvetronic and VANOS variable valve timing technology. Output now sits at 230 hp at 6,500 rpm, up 15 from its predecessor, and 200 lb-ft of torque at 2,750 rpm, again up 15 lb-ft. The factory says 0-100 km/h comes in 6.9 seconds. Six-speed manual or Steptronic automatic gearboxes are available with the new DOHC mill, along with a $62,500 528xi model, sporting BMW’s xDrive all-wheel drive system.

Up from the base Fiver, the $68,900 535i (previously the 530i) now touts the award-winning twin-turbo inline six. As in the 3 Series, the forced-induction mill wears individually calibrated turbos for low and high-end torque, meaning virtually no lag off the line. Combined with valve timing trickery similar to the base engine, the 535i makes 300 hp at 5,800 rpm and 300 lb-ft of torque at 1,400 rpm, up a noteworthy 45 ponies and 80 lb-ft over last year’s model. Naught to 100 takes just 5.9 seconds. Again, the available gearboxes are either a six-speed manual or automatic.

Though we couldn’t try it, both the 535i and 550i offer a new Sport Automatic package with paddle shifters, rpm-matching downshifts and a Sport button for quicker shifts. AWD is offered too on the $71,500 535xi.

As luck would have it, the first keys handed to us in Sin City belonged to none other that that Bavarian barnstormer, the $113,300 M5. A disclaimer: I’d never driven said fourth-gen E60 M despite its years on the market, so this Teutonic rocket was an all-new experience.

It did not disappoint. We spent the latter part the afternoon blazing across flat, lunar-like open desert towards the historic, and aptly named Furnace Creek Inn & Resort Ranch in Death Valley, California.

Photo ops meant stepping into scorching 103-degree heat — even at six in the evening. The nether regions of Death Valley possess this muffled, supernatural quiet, broken only by the click of our camera shutters and the tick of the M5’s hot exhaust.

With 500 hp and 383 lb-ft of torque available to a heavy right foot, asphalt stretching to the shimmering horizon was devoured with aplomb. Zero to 100 takes just 4.7 seconds.

The only blemish in the M’s armor remains the seven-speed Sequential Manual Gearbox (SMG), which despite improvements for ’08, remains a lackluster match to the V10 songstress. Shifts often come hard or disconcertingly late, especially when pulling out to pass. Happily, a traditional six-speed manual is now standard, a move brought on by enthusiasts’ demand.

All ’08 5 Series receive styling mods, including a flush-mounted grille, a new front valence, recontoured side sills and revised tail- and headlamps, but really only BMW aficionados will be able to tell the difference. To me, the new lines clean up the sedan’s looks considerably, though I still can’t help thinking of Dame Edna when I see those headlights…

Day 2 took us from the oven that is Death Valley to the cooler, higher-altitude climes of Yosemite National Park (with a worthwhile stop at the fittingly-named Really Good Fresh Jerky stand in the town of Olancha, CA). A pair of forced-induction 535i’s provided transportation, in rear- and all-wheel drive guise, both wearing six-speed manual gearboxes.

Really, it’s difficult to make a case for stepping up to the V8 “5” given the buttery brutes these mid-level models are. Being only 30 kg (66 lbs.) heavier than the similarly engined 3 Series, the 535’s are nearly as vivacious as their smaller siblings, meaning more than enough chutzpah for most drivers.

All 2008 5 Series’ wear revised interiors focused primarily on upping the vehicle’s luxury quotient. A new steering wheel, copious new trim bits, one-piece leather and wood-clad door panels and a redone iDrive control knob lead the cause.

In a refreshing aside, a BMW spokespeople actually admitted that “the basic iDrive needs some work” and that the much-maligned control system operated via said control knob and a display screen is “still not where we’re comfortable with it.” Nonetheless, the 5’s iDrive has been revised with six programmable “favourites” buttons for frequently used features.

There’s also a new  “Shift-by-wire” gear-stick for Steptronic automatic models. Looking like something swiped from the Millennium Falcon, it debuted on the new X5 SUV, dumping the tradition PRNDL gates for push button “Park” selection and rocker-style gear changes. It’s pretty cool looking, though admittedly gimmicky.

The morning of day 3 began at the wheel of a base no-frills 528i sedan. BMW’s route took us though the heart of Yosemite, past El Capitan, the 1,000 m (3,000 ft.) granite wall prized by fearless climbers, and Bridalveil Fall, which native people believed was home to a vengeful spirit guarding the valley entrance.

We escaped the Sierra Nevadas unassailed by any ghouls, motoring down to California’s citrus-rich farm plains and perhaps the most entertaining piece of tarmac on the trip — the aptly named Ben Hur Road, a writhing spaghetti noodle through the foothills between Mariposa and Raymond, California.

Surprisingly, the route showed the 528i to be our favourite 5 of the flock. Its lightweight engine and lack of extra (heavy) gizmos meant flat, fast turn-ins and apex exits. The six-speed shifter had to be rowed abundantly to summon the desired power from the inline six, but their combined smoothness only added to the experience.

As expected, the press bumph on the revised 5 Series is implausibly dense. Technology highlights include active cruise control with a new Stop & Go feature, useful in heavy traffic; a new lane-departure warning system, which vibrates the steering wheel if the 5 cross a line without signaling; new USB connectivity for iPods; a head-up display; night vision and active steering.

After a gargantuan lunch of Chimichangas at a local Mexican eatery, we thought it best to let the 5 Series’ navigation system guide us on a direct route to Monterey, rather than stomaching another road like Ben Hur.

Looking to make haste, we commandeered an $82,900 550i, which paired BMW’s 4.8-litre 32-valve V8 (360 hp/360 lb-ft) with a six-speed automatic gearbox. As mentioned the twin-turbo I-6 really is all the engine most drivers could ask for, but the eight-pot 5er does exude a certain Bavarian substantiality its inline brethren lack.

The 550i is easily the best looking of these Bimmers too, thanks to a new standard M Sport Package which bolts on M aerodynamic styling, staggered width 19-inch wheels, an M Sport exhaust, sport seats and an M steering wheel.

Our jaunt with the revised 5s officially ended on Cannery Row, the seaside district made famous by John Steinbeck’s novel of the same name. In three days we’d traveled from barren desert to beachfront without crossing a state line. BMW’s reworked 5 Series is much the same, offering a sundry of takes on the midsize sport sedan from the same fraternity.