1. Will Toyota run away at the head of the field?

Toyota topping the timesheets at the Prologue test at Paul Ricard last month came as no surprise, although the sheer size of the gap to the privateers - 4.372 seconds, to be exact - was a shock to some. But that figure doesn't quite tell the full story.

Given the two TS050 Hybrids will be running this weekend in low-downforce spec, the relevant gap to the third-placed #11 SMP Racing BR Engineering BR1-AER is cut to 2.883s. And, remember, both Toyotas ran outside of the Equivalence of Technology rules at the Prologue for its best times, and then lapped slower than the leading privateer cars once they returned within the regulations.

It's against that backdrop that the WEC's rulemakers decided to reduce the energy available per lap for the non-hybrids, from 1.69x compared to the Toyotas at Paul Ricard to 1.38x at Spa. The privateers have also been hit with a fuel decrease, going from 54kg to 47.1kg per stint (versus 35.1kg for Toyota).

The goal is to try and reach laptime parity between the Toyotas and the non-hybrids, but the Japanese brand's real advantage lies in fuel economy. Its promised one-lap advantage at the Le Mans 24 Hours translates to two laps at Spa, which is likely to mean one less pitstop over the course of the six hours.

That's a major advantage, particularly as the benefits of running a hybrid system will make Toyota hard to beat in qualifying - and hard to pass in the opening stint. If any of the privateers stand a chance, they need to be out front building a buffer to give themselves the ability to make that extra stop.

#7 Toyota Gazoo Racing Toyota TS050: Mike Conway, Alexander Wurz, Jose Maria Lopez, Sébastien Buemi, Anthony Davidson Photo by: JEP / LAT Images

2. Who will emerge as the best of the non-hybrids?

The other big unknown is which of the privateers it will be that leads the Toyota chase. The sheer number of test miles the Dallara-built BR1 has accumulated makes it the logical contender, but the slender gap to the Rebellion R-13-Gibson at Paul Ricard may be a cause for concern.

While the BR1 is said to have completed over 5,000km in testing, the first Oreca-designed R-13 was only built up at the start of the week of the Prologue, being shared by all six drivers, and the second car wasn't shaken down until a private test at Magny-Cours last month.

While Neel Jani said that Spa will be a "learning" race for Rebellion, it would come as little surprise to see the Swiss team lead the privateer charge given its Prologue speed, assuming the R-13s are reliable, although the two factory BR1-AERs are likely to not be far away either.

The pair of Ginetta-Mecachrome being run by Manor were a little further off at Paul Ricard, both in pure speed and mileage terms. But WEC newcomer Oliver Rowland, who delivered the team's best time in the #6 car, remains bullish about the G60-LT-P1's prospects for Spa - despite a 20km/h shortfall in the speed traps compared to the best of the BR1s in the Prologue.

That leaves ByKolles, which is running essentially the same car as last year but with aerodynamic improvements that, according to Dominik Kraihamer, have made the Nissan-powered ENSO CLM P1/01 "more stable, with more grip everywhere". After a Prologue test where it racked up more laps (331) than any of the other privateers, the Austrian squad will no longer be LMP1's laughing stock.

#1 Rebellion Racing Rebellion R-13: Andre Lotterer, Neel Jani, Bruno Senna, Mathias Beche, Gustavo Menezes, Thomas Laurent, #4 ByKolles Racing Team Enso CLM P1/01: Oliver Webb, Dominik Kraihamer, Tom Dilmann, Kang Ling, #11 SMP Racing BR Engineering BR1: Mikhail Aleshin, Vitaly Petrov Photo by: Paul Foster

3. Alonso finally makes his WEC bow

There's no getting away from the fact that many people who tune in to catch the action from Spa this weekend will be paying special attention to one man in particular: Fernando Alonso.

In a way, it already feels like Alonso is a sportscar racing veteran. It seems a long time ago since he made his rookie test appearance for Toyota in Bahrain last year, making an immediate impression on the team, and since he entered the Rolex 24 at Daytona in a United Autosports LMP2 car.

The Spaniard's primary target - as well as Toyota's, obviously - is victory in the Le Mans 24 Hours, as he bids to become only the second driver in history to win motorsport's Triple Crown. But he has made it very clear he wants to win the WEC title too, and that quest begins this weekend at Spa.

Even if Toyota does have an advantage over the non-hybrid opposition, there will still be a fierce rivalry between the two TS050 Hybrid crews, as Alonso and squadmates Sebastien Buemi and Kazuki Nakajima take on their counterparts Mike Conway, Jose Maria Lopez and Kamui Kobayashi.

Barring any surprises, it will likely to come down to which crew makes fewer mistakes, and Alonso's role in that is sure to be key, given his relative inexperience. But the good news for Buemi and Nakajima is that his drive at Daytona was virtually flawless, so expectations are justifiably high.

#7 Toyota Gazoo Racing Toyota TS050-Hybrid: Fernando Alonso Photo by: Toyota Racing

4. Other famous names make their debuts

While Alonso will be the centre of attention at Spa, he won't be the only notable name making his first start in the WEC - and not even the only former F1 race winner.

Almost six years on from his triumph with Williams in the Spanish Grand Prix, Pastor Maldonado will join Roberto Gonzalez and Nathanael Berthon in DragonSpeed's Oreca LMP2 for his first taste of endurance racing, and from Silverstone onwards he'll be partnering a certain Anthony Davidson.

"It’s going to be fun," Davidson said of sharing a car with Maldonado. "He’s obviously a really quick driver, I know him off-track as well; he’s a really nice guy. I’m looking forward to getting to know him even more, and introducing him to a very different world to F1. I’m expecting him to be bloody fast!"

Among the other drivers debuting at Spa are F2 race winner Rowland, who joins the Manor LMP1 team for the full 2018/19 season, and Formula V8 3.5 champion Pietro Fittipaldi, who is deputising for Renger van der Zande in DragonSpeed's LMP1 BR Engineering BR1-Gibson.

Later in the year, there will also be the small matter of another F1 champion, Jenson Button, making his WEC debut with the SMP Racing LMP1 team. But a clash with Super GT at Fuji this weekend means Mikhail Aleshin and Vitaly Petrov will have to pilot the #11 BR1-AER as a duo.

Pastor Maldonado, Dragonspeed Photo by: JEP / LAT Images

5. BMW joins the GTE Pro party

And then there were five. Joining an already well-supported GTE Pro class for the WEC superseason is BMW, which will take on Ferrari, Ford, Porsche and Aston Martin for category honours.

It's a big ask, but the all-new M8 GTE already has 36 hours of race action under its belt this year thanks to two IMSA WeatherTech SportsCar Championship appearances at Daytona and Sebring, where the German marque secured pole position and a runner-up finish in the GT Le Mans division.

That followed a well-timed Balance of Performance adjustment for BMW, the legacy of a disappointing first race outing in the Rolex 24, although the MTEK-run WEC M8s will start the season 35kg heavier than the RLL-run ones that raced in the Sebring 12 Hours.

"At the end of the day, you never get what you probably expect, but you have to accept where you start and go from there," said Marquardt of BMW's starting BoP at Paul Ricard, where the best M8 lapped a full 2.5 seconds off the pace of the quickest of the Porsches.

"If you look at the races last year, it proved that the system is working well. We just have to see this year how it works with new players on board, because we're not the only new car in this championship this year," he added, referring to Aston Martin's new-generation Vantage that also debuts in Spa.

#82 BMW Team MTEK BMW M8 GTE: Augusto Farfus, Antonio Felix da Costa, Alexander Sims, Tom Blomqvist Photo by: Paul Foster

6. Who will show their cards ahead of Le Mans?

Unusually, there is just one race this year before the Le Mans 24 Hours, with Spa providing the only chance for teams to prepare for the big one owing to the WEC's transition to a winter calendar.

Inevitably, for the GTE Pro teams, getting a favourable BoP is all part of the game - and while the system is now automated for the six-hour races, the unique demands of the Circuit de la Sarthe mean the BoP for the twice-around-the-clock classic is still set manually.

The organisers in theory retain the right to tweak the BoP at any time prior to Le Mans, and in 2016 a change was even issued after qualifying. But Ford driver Harry Tincknell believes it's much harder now for manufacturers to game the system now than it was in previous years.

"People with a new car or an updated car might [hold back at Spa]," said Tincknell. "But I think the ACO and the FIA are fairly wise to it. You're not going to bring out a new car or an update and go slower, so if you're messing around it should be easy enough to see.

"Whether we'll see the true potential though, I don't know. From our side it's great because we've got the same car [as last year] so we know where we should be. If people want to sacrifice points at Spa, we'll capitalise on that could make the difference at the end of the championship."

#67 Ford Chip Ganassi Racing Ford GT: Andy Priaulx, Harry Tincknell Photo by: JEP / LAT Images

7. A pair of champions return to WEC

Last season was notable for the absence of one of the WEC's longest-serving drivers, Gianmaria Bruni, who was exiled from the paddock for a year as a condition of getting out of his long-term Ferrari contract in order to join rival GTE Pro squad Porsche.

In that time, Bruni dabbled in IMSA, scoring a pair of second-place finishes in the mid-engined 911 RSR, and now he's back to form a formidable partnership with Richard Lietz in the #91 Manthey-run car.

"Porsche was keen to keep me even if I was not racing for six months," Bruni said. "I was even happier with the decision [to leave Ferrari], because it means they really wanted me.

"Of course I have to [change my driving style], because the car is completely different. When I started testing, we couldn't change anything because the car is frozen until the end of the superseason. So I have to adapt, and obviously it’s not perfect for my driving style, but you have to use what you have."

Bruni's old partner-in-crime Giancarlo Fisichella, meanwhile, is embarking on his first full WEC season since 2013 - although the three-time F1 grand prix winner will race in the GTE Am division, joining forces with Thomas Flohr and Francesco Castellacci in the Spirit of Race Ferrari team.

#91 Porsche GT Team Porsche 911 RSR: Richard Lietz, Gianmaria Bruni Photo by: Paul Foster

8. An LMP2 battle that's too close to call

The LMP2 field may be down to only seven cars for the new campaign, but there's a lot more variety - with full-time entries from Dallara and Ligier taking on dominant brand Oreca, and Michelin rejoining the fray to take on previous class monopolist Dunlop.

The margins at the head of the field at the Prologue were fine, with Maldonado putting the DragonSpeed Oreca 07 only three tenths clear of Nicolas Lapierre in the Alpine-badged Signatech Oreca. Racing Team Nederland managed to get its Dallara P217 within six tenths of the pace, too.

Despite that narrow defeat, Signatech probably begins the year as marginal favourite, particularly as it boasts possibly the strongest silver in this year's field, Pierre Thiriet - who moves to the French team after a tumultuous season with G-Drive Racing that was cut short.

"On paper, I think we have everything we need to appear at the top of the table," said Thiriet. "I do not want to say too much, because last year, we had something that worked very well on paper [at G-Drive], but the human element is super important.

"Here [at Signatech], I am much more positive because everything works well on the human side. It is much easier as a Frenchman to work with a French team."

#36 Signatech Alpine Matmut Alpine A470: Nicolas Lapierre, Andre Negrao, Pierre Thiriet Photo by: Paul Foster

9. Iron-man Duval set for double duty

Unlike BMW counterpart Augusto Farfus, Loic Duval has Audi's blessing to undertake the WEC/DTM double this weekend, involving two rapid trips between Hockenheim and Spa.

While Audi has been clear that the DTM is the priority for Duval, the plan has been made possible by the fact that WEC action begins on a Thursday, and ends on Saturday, leaving him free on Sunday.

That means the Frenchman can participate with his TDS Racing LMP2 squad as normal during Thursday's two free practice sessions at Spa, before high-tailing it to Hockenheim - leaving squadmates Francois Perrodo and Matthieu Vaxiviere to qualify the car on Friday.

Once he's dealt with the small matter of the DTM season-opening race on Saturday, which finishes at 1430 local time, Duval will then make the 300km trip - "probably by helicopter", according to TDS boss Xavier Combet - back to Spa in time to take over the TDS Oreca 07 for the final stages of the race.

Then it's straight back to Hockenheim for the second DTM race on Sunday. Sounds easy when you put it like that, doesn't it?

Loïc Duval, Audi Sport Team Joest Photo by: Audi Communications Motorsport

10. Can the Ams trouble the Pros?

One unusual thing about the WEC Prologue timesheets was that the two best GTE Am class cars were the fifth and sixth-fastest GTE cars overall, behind only the two Pro class 911s and the two Ford GTs.

This has raised the prospect of the Am cars mixing it with their Pro cousins at Spa, particularly as they are not subject to the same tyre restrictions.

"The amateur cars are not limited in their tyre choice, they can take new tyres at every pit stop, while we have to drive double stints," Porsche GT boss Dr. Frank-Steffen Walliser pointed out.

"There may be a small difference in the performance of cars in both classes, but if the professional driver in a GTE-Am car has a fresh set of tyres, he will fly past the top pro guys on old tyres. They'll be a second or two faster at times. It's absurd."

Either way, it seems the Porsche is the car to have in GTE Am, with the four 2017-spec 911 RSRs locking out the top four positions in class at the Prologue. The best of the rest, TF Sport's old-spec Aston Martin Vantage, was more than a second off Matteo Cairoli in the pace-setting Proton Porsche.

#88 Proton Competition Porsche 911 RSR: Khaled Al Qubaisi, Giorgio Roda, Matteo Cairoli Photo by: JEP / LAT Images

Additional reporting by Gary Watkins, Roman Wittemeier and Basile Davoine