The issue with attempting to coax new manufacturers in to supercars is that the series is at a low point commercially. Ford and Holden are at an extremely low level of investment into the series, the switch to Foxtel based telecast has had a large effect on sponsor revenue to teams. This revenue piece is becoming obvious to results - the teams that have the large operating budgets are wining all the races, the teams that do not, are not winning. The cycle remains that sponsors want to invest in teams that 1)win, and 2) get a lot of TV time. Which are the big teams that already have the budget.
Supercars as a group saw this decline in manufacturer involvement coming - with Ford pulling out and Holden reducing teams input and spend, with Mercedes not becoming more involved with the Erebus project and Volvo pulling the plug. That is the reason that they have opened the rules up to allow coupes and various engine profiles to be homologated. The issues with this are - they are alienating to a point the core fan group as the 'V8s' has always been the blue collar sport, and that demographic will struggle to get behind twin turbo Hyundais for example. But the people who are attracted to that style of car will be less likely to follow the sport as it is seen from the outside a 'the V8s".
The second major issue is the spend required from teams and manufacturers to bring in a new car, with very little confidence that the car or specification will be competitive. Take the Volvo vs Nissan chassis/engine combos. Volvo 'got lucky' that the chassis presented and aero package homologated was very drag efficient, but didn't necessarily have the downforce levels of Ford/Holden. This led to it being a chassis that could be untouchable at some circuits and back in the pack at others, depending on circuit profile. The bonus was that at least it was able to win some races when the stars aligned, if not challenge for a championship due to inconsistency. Compare that to the Nissan, which was homologated with essentially no stand out strength - it was a little down on power, a little down on downforce, and had a bit more drag due to vehicle profile. That manufacturer has struggled to get any sort of results for its entire time as a Supercar team, to the point where they have decided the investment is no longer worth while.
While Supercars continue to run homologations tests with fairly antiquated methods such as 'roll down' tests on airstrips, this variance in chassis performance will continue - and once homologated, its VERY hard to update deficiencies.
Now look at this from a manufacturers point of view.
-Is the series strong commercially? - its not collapsing, but it was much stronger a decade ago. I use the litmus test of mid-rear of pack team sponsors - I look at them now and have no idea who half the companies are. A decade ago they were nearly all 'name' brands.
-Does the series have good visibility to the public? - with the addition of the Fox deal, no. Arguably (and supercars will push this point heavily) the telecast has never been better, and has more hours on screen than ever before. The issue is that is is generally only the 'die hard' fans that actually see this - and they will watch regardless. What this model has lost is the fringe fan or non-fan who may tune in accidentally on a Sunday because they are channel surfing.
-Is the manufacturer able to invest a sensible amount of money to be competitive? Probably not - I know in my day the teams operating budgets were in the vicinity of $6-10Million dollars a season. I would expect that the 2 big teams - Triple8 and Penske/DJR are now operating on significantly more than that. And the gap from those teams to the rest is getting larger every year, so arguable an investment LARGER than those teams is required, because they are refining existing competitive packages, not developing form scratch.
-Once that investment is made, is there any guarantee of success? No. The Mercedes/Volvo/Nissan examples all had limited success based of having a similar chassis Engine combo as the existing manufacturers.
-Is bringing a new chassis/engine configuration into the series likely to have success? Maybe. I see it as the highest risk, highest reward. To use the Volvo as an example - that combo had strengths and weaknesses when compared to the status quo. But the positive was that the 'strengths' - essentially low drag straight-line speed - was stronger than its competitors, allowing some level of success at specific circuits. We have seen how a package that isn't quite comparable to the existing really has no chance of victory in the Mercedes. And that is with a 4 door V8 model very similar to its competition. Now introducing a twin turbo 2 door for example opens the door to massive aero variances, and power levels, but more importantly power delivery. Depending on homologation restrictions, these combination may have a higher torque, lower top end power for example, which means they may be untouchable at Winton, but irrelevant at Bathurst. They may get lucky and have a combo homologated that has circuits that it excels, and it may also turn into a Mercedes, and that is not a very attractive proposition.
-Can a manufacturer enter with an existing team such as Kellys and be confident of their level of expertise to take them to the top? Probably not. The larger teams are now all using a lot of international linkups or were built up using those links. I was working at Triple8 during the Briggs/T8 change over period, and there was a level of international expertise using T8 UK, and bringing in Ludo from DTM that was above anything that team had done before. Penske obviously has strong technical alliances with their US bases. Walkinshaw now have access to the Andretti technical team. These links are proving to separate the haves from have nots -the the point where it is increasingly hard to field a car without a technical alliance to a top team. Tickford and BJR for example are dropping off the podium as they cant keep up with the pace of development of the top teams due to resourcing.
So really, why would a new manufacturer come in to the sport? Supercars have been very very blessed since the early 90's that Ford and Holden had extremely similar chassis and engine combos, and both invested heavily in the series. These could roll out every year with an extremely balanced level of performance. The past few years has proven that 'balance of performance' is a very difficult thing to manage.
I hate to say it, as I think it goes against racing in its purist form, but if they want to make the series attractive to other manufacturers, they need to bring in manufactured and adjustable performance limiters such as air restrictors and success ballast. These have worked in other series globally to keep all manufacturers relevant.
To use KIA as an example - they currently have a perception within the mainstream that they are a low cost hairdressers car. I know that they are battling this with introducing vehicles like the Stinger, but they are battling the existing perception. It would be a huge risk to enter Supercars when there is a very real possibility that they will not be able to field a race winning car, and only solidify the perception that their vehicles are not the equal to traditional Aussie cars such as Ford and Holden.