Who is winning the BTCC's five-way manufacturer war?

Fifteen races down and 15 to go, the fight at the head of the British Touring Car Championship is close. Just 20 points cover the top four drivers, and they are all in cars from a factory stable with a Honda, two BMWs and a Subaru in the mix.

The series resumes at Snetterton on July 29, with just two-and-a-half months to determine who will claim this year's silverware.

BMW
Championship position: 1st
Best-placed driver: 2nd (Rob Collard)
Wins: 6
Poles: 0
Podiums: 13

Becoming a full factory BMW team for the first time has ramped up the pressure on WSR, which is operating the 125i M Sports. But pressure is something that WSR can handle, and all of its drivers are in the top seven of the points positions.

Fitted with the new bespoke two-litre turbocharged engine, dubbed the B48, the switch to a more modern motor has not been without its problems. There have been numerous engine changes, which will ultimately cost the team points in the manufacturers battle if they continue.

The Team BMW arm, which Colin Turkington and Rob Collard race under, have used three of their allocated four engines already. Andrew Jordan, who runs under the BMW Pirtek Racing colours, has used one of his two.

Also, Turkington's car has been blighted by a top-end misfire, and dropped out with damage at Oulton Park, costing him a raft of points - which was particularly painful on a circuit that traditionally suits rear-wheel-drive cars.

There is Knockhill coming up which will suit the 125i M Sports, but the remainder of the season will be a pretty level playing field between WSR and its rivals.

HONDA
Championship position: 2nd
Best-placed driver: 1st (Gordon Shedden)
Wins: 3
Poles: 2 (Plus one for customer team Eurotech)
Podiums: 8

The Team Dynamics Honda Civic Type R was the best chassis in the British Touring Car Championship in 2016, and there was not a lot that the team could do to it ahead of the new season other than to "tickle it", as reigning champion Gordon Shedden said.

Honda introduced a new engine last season and most of the development work was done over the early part of 2016.

But there have been developments in the handling department this season. The poise of the chassis when the drivers are on the power, as the weight transitions to the back, has been one of the key features that have helped Matt Neal and Shedden to three wins from the 15 rounds held so far. Shedden is top of the standings by 11 points, and he has got his bogey circuit of Croft out of the way without losing too much ground to the rear-wheel-drive cars that so love the North Yorkshire venue.

Shedden has also been unlucky, and he lost a win at Donington Park when his car was found to be running too low - a slip the team later admitted to as it rapidly changed the car to a wet-weather set-up after a sudden downpour.

SUBARU
Championship position: 3rd
Best-placed driver: 4th (Ashley Sutton)
Wins: 2
Poles: 1
Podiums: 8

Team BMR's season has been a story of two halves so far in 2017. There is the rocket ship that is up-and-comer Ashley Sutton, who has won two races and is fourth in the points, and then there is two-time champion Jason Plato, who has had a nightmare.

A rule tweak at the start of the season meant that the Levorg machines were forced to carry weight further up in the car to cancel out the inherent advantages of a low-slung boxer-configuration engine (which was one of the reasons Team BMR chose the Subaru in the first place).

Plato had a crash at the opening round which badly damaged the chassis, and he says that the crash damage could be one of the reasons that he has a car that simply can't rid itself of understeer, no matter what the engineers do to it. There are no answers coming, and there is a very tense atmosphere in one half of the BMR garage.

Josh Price and James Cole are struggling similarly, too. Only Sutton has managed to get the most from it. The car was granted a bit more boost for Oulton Park, and Sutton won there and then at Croft, too. His driving is superb and his overtaking remains the best on the grid. He said he had to make hay on the circuits that suited the rear-wheel-drive cars and he did. The rest of the season might be more of a struggle for him.

VAUXHALL
Championship position: 4th
Best-placed driver: 14th (Tom Chilton)
Best result: 3rd
Poles: 0
Podiums: 1

It was very ambitious for the Power Maxed Racing team to take on the build of a new NGTC-spec British touring cars. The team had only been fully established in 2016 and had just run customer cars up until that point, but the new Astra hit the circuits on media day and immediately turned heads.

PMR recruited well ahead of the season, with Martin Broadhurst coming on board from Triple Eight, and other engineers coming from chassis builder Willie Poole Motorsport Services. They clicked together well.

The raft of bespoke control parts in the modern-day BTCC have helped speed up the process of getting to grips with the car, and the feedback of tin-top old hand Tom Chilton has helped the car reach the sharp(ish) end.

Chilton's initial race weekend provided a podium, but that flattered the car and the team. As others have got on top of their mounts, the Vauxhall has slipped back to the fringes of the top 10, but is capable of claiming a podium in a reversed-grid race.

The Astra is reliable, but more pace needs to be found before the car can battle for titles.

MG
Championship position: 5th
Best-placed driver: 22nd* (Aron Taylor-Smith, Josh Cook 13th but swapped teams)
Best result: 7th
Poles: 0
Podiums: 0

The MG6 has always been a heavy car, because that was the way it was built as a road car. Its steel construction means that it is a tough car to make work on a race track.

There has been little development on the saloon car since it was created, apart from the upgrade to the new RML parts for this season. That was actually a double-edged sword for the squad as the hybrid of older GPRM-derived parts and RML parts last season gave the car an advantage in changeable conditions.

The car has slipped back down the pecking order as others have improved, and it appears that there is no way that the crew can climb back up.

Dan Lloyd quit the team after barrel-rolling out of Thruxton, and was replaced by the returning Josh Cook. Aron Taylor-Smith broke his leg in a qualifying accident at Croft, but is likely to return for Snetterton at the end of the month.

There has also been a turbulent time in terms of the staffing at the team - and not only the drivers. Ian Harrison has missed the last two rounds while away on other commitments, with former Team BKR boss Nico Ferrari assuming charge on a temporary basis.

It is not yet clear whether or not Harrison will return. There are tough times ahead.