RACER web editor Tony DiZinno looks at the field for this weekend's Petit Le Mans. This time: the GT classes.

CORVETTE – With the driver, manufacturer and team championships clinched last race at VIR, you might think Corvette Racing has nothing to fight for, but you'd be wrong.

Oliver Gavin and Tommy Milner wrapped the drivers title with their fourth win of the season. A win for them (with third driver Richard Westbrook) or a win by the sister car driven by Jan Magnussen, Antonio Garcia and Jordan Taylor would net Corvette a fifth in 10 races for an excellent hit rate of half the wins, easily their best since moving into GT with the GT2-spec C6.R halfway through 2009. Corvette won only one ALMS race in each of 2010 and 2011.

A win for the latter trio would be particularly huge, given Magnussen's streak of a win in each ALMS season is on the line and it would secure second place in the drivers' championship for he and Garcia. It's a result he's already achieved once, as two years ago, Magnussen, Gavin and Emmanuel Collard took the win on the final lap as the Risi Competizione Ferrari F430 GT ran out of fuel.

PORSCHE – An additional ELMS RSR that will run in GTE Am (Imsa Performance Matmut) joins the usual quartet of Porsches, but the focus will primarily be on the full-season entries on the ALMS side.

Despite a fraught start to the season with only 19 points scored from the first three races, Flying Lizard Motorsports could still secure second in the drivers' standings with Patrick Long and Jorg Bergmeister. In the last six races, the pair has a win and three runner-ups, and had another win at Mosport taken away after failing the post-race stall test. That run has lifted the two to just two behind Magnussen/Garcia (Corvette) and in a tie with Extreme Speed Ferrari's pairing of Johannes van Overbeek and Scott Sharp. Patrick Pilet joins Long and Bergmeister in the lead No. 45 car.

Each of the others has improved lineups for this race. The second Flying Lizard car adds Nick Tandy alongside Porsche factory shoe Marco Holzer and team principal Seth Neiman; this is a lineup of young, quick drivers who could be able to lift this car to a top-five finish in class.

Baltimore winners Team Falken Tire bring in Martin Ragginger alongside Bryan Sellers and Wolf Henzler, as they look to end on a high note after an at-times frustrating season. Underrated and perhaps on pace to surprise yet again is Paul Miller Racing, actually the top-finishing ALMS Porsche at Sebring, in fifth, with the lineup of Sascha Maassen, Bryce Miller and Richard Lietz, another Porsche factory driver.

FERRARI – What's been a markedly improved third season for the Extreme Speed Motorsports has seen the team score its first victory and contend for second in points as the No. 01 Ferrari F458 Italia has been a regular podium finisher. Now, the team seeks its first win on track as its win at Mosport came via a disqualification, and this race, Ferrari factory driver Toni Vilander joins regulars Scott Sharp and Johannes van Overbeek.

The sister No. 02 was originally entered in the GT AM subset class, which meant it could only have one Platinum or Gold-rated driver by the FIA alongside a combination of two Silver or Bronze-rated ones. That changed to see the car back in the usual GT class, with Patron Spirits CEO Ed Brown joined by usual co-driver Guy Cosmo and Anthony Lazzaro.

A third Ferrari is entered from AF Corse, the team that won GT last year, although the 2011-spec 458 fielded by the team in the AM class is an ELMS entrant that will likely be the slowest of all GT cars based on its driver lineup.

BMW – Petit Le Mans marks the end of an era for BMW, as the latest iteration of M3s is set to run its final race. These M3s came back in 2009, winning its first race later that year at Road America, and then were most successful in the 2010 and '11 seasons, the latter year where BMW swept the driver, team and manufacturer championships.

Regretfully, one of BMW and BMW Team RLL's stars, Joey Hand, won't be present at Petit – the American's DTM duties take precedence. His replacement, Jonathan Summerton, will then be ALMS GT's busiest driver as the 23-year-old Floridian will race in both the team's entries (and the only driver in class to do so). It's a big ask and a big task, but considering how well he kept his head on his shoulders in his first ever endurance race at Sebring in March (he won with Hand and Dirk Mueller), he should be good to go.

Summerton's presence as the third driver – compared to the second in the No. 56 car – should aid the No. 55's chances going into the race. He'll have less pressure to perform in that car alongside veterans Bill Auberlen and Jorg Mueller, while Dirk Mueller might need to do the lion's share of the work in the No. 56. Uwe Alzen returns but is unlikely to match the pace of his younger co-drivers. Hand's loss this race is magnified and BMW may have to rely on guile and strategy if not outright pace to bookend the season with wins and send the M3 out on a high note.

VIPER – This is SRT Motorsports' biggest test to date. The Vipers return for the first time since Baltimore, where the No. 91 failed to start following a heavy practice accident by Dominik Farnbacher. Since that date, for more than a month, it's been a thrash to rebuild and reload one of the team's two cars.

Both driver lineups are bolstered – IZOD IndyCar Series champion Ryan Hunter-Reay makes his much anticipated Viper debut alongside Farnbacher and Kuno Wittmer, while Jonathan Bomarito partners with Tommy Kendall and Marc Goossens in the sister No. 93. Both RHR and Bomarito have endurance experience, although RHR's has been in prototypes whereas Bomarito, a Mazda RX-8 veteran, is well suited to the rigors of GT endurance racing.

With a class win unlikely, the goal for both cars has to be to get to the end and put a period on the brief debut season.

LOTUS – Rather quietly, Alex Job's squad has improved the second half of the season. This marks the Evora's second endurance race (six-plus hours) in Job's hands; barely sorted at Monterey, the car retired early in May.

The disadvantage of having a gentleman second driver in Bill Sweedler is negated for a longer-distance race. He and Townsend Bell are joined by the most experienced Evora driver on the market in Lotus factory shoe Johnny Mowlem, who will be able to provide a wealth of feedback and insight into the car.

Like the Viper, it's not an outright threat on pace but can set itself up for a strong finish simply by circulating and avoiding reliability pitfalls. And, to be fair, Bell and Sweedler already have an endurance race victory this year – they co-drove AJR's winning GTC class entry at Sebring with Dion von Moltke.

GTC – ALMS' least heralded and perhaps least appreciated class ends its season with a respectable seven-car entry, although only four of the cars have run full-time. Cooper MacNeil clinched the class title at VIR co-driving with Leh Keen, and for the second time this year Alex Job Racing has played the driver ratings card to its advantage in signing a third driver who is probably better than his FIA classification would indicate (von Moltke is a Silver-rated driver).

Poor luck has tended to strike the other full-time cars for the rest of this year. Green Hornet, for instance, has only a single win despite Damien Faulkner's run of poles – poor luck has struck the green No. 34 in almost every race this season. TRG has been rather inconsistent, not for anything Spencer Pumpelly has done but more for fluidity in his co-drivers, all who start the race and tend to hit trouble. JDX has improved from its first season and nabbed its first win at Mid-Ohio, but not with its normal driver lineup – Michael Valiante is a better talent than his results would indicate.

The part-timers are Competition Motorsports, back again with helicopter movie pilot David Calvert-Jones, an IMSA GT3 Cup regular making his ALMS debut alongside its two normal drivers. NGT has two cars entered but neither has an inspiring driver lineup.

The most glaring omission from the class field is Jeroen Bleekemolen, who won his first three starts in class this year for three different teams (TRG, JDX, Job) and was second for NGT last race at VIR. He is racing in the Australian V8 Supercars' event at Surfers' Paradise as one of the guest drivers this weekend. With only one Platinum or Gold-rated driver allowed, the generally accepted fastest driver in class won't be in this year's field – which opens the door for most of the entries to take a class win.