VX Racing team boss Ian Harrison has admitted that the organisers of the HiQ MSA British Touring Car Championship have to be careful that the series doesn't become a two-tier championship with diesel power holding an advantage over petrol machinery.

While Vauxhall was able to wrap up the manufacturers' title at Silverstone, with a lead of 121 points over SEAT and 81 available at Brands Hatch on Finals Day, the diesel-powered Leon TDi again emerged as the car to beat in terms of pace, with Jason Plato and Darren Turner locking out the front-row of the grid for the fourth meeting in a row.

While that has led some in the paddock to question whether or not the diesels have an unfair advantage, and has led to much discussion amongst fans, Harrison conceded that it wasn't easy for officials to ensure a level playing field throughout the grid.

However, he admitted that the series had to be careful that it didn't end up with a situation where there would effectively be two separate races on track.

"The diesel car has made it a completely different game," he told Crash.net Radio. "With all the other cars we have competed against, the only difference has been whether it is front or rear wheel drive. They are all petrol engines with the same horsepower and perform the same, and you can see that on the grid as it is so tight with the petrol cars. It shows things are pretty right in terms of the regulations and the equivalency that is written into them.

"The diesel thing is another issue as they obviously have an advantage in horsepower and it is very difficult for people - and I understand this - to regulate that and make sure that it is a close championship. At the end of the day though, we have to look at the big picture. It isn't about us and SEAT or us and BMW, or us and anybody for that matter. If someone comes in with a gas car, it's all about that car competing and everyone else competing with it at the same level.

"What we don't want is a situation where there are two cars with three-tenths of a second advantage over everyone else and the rest from third to 17th then covered by a second, which is almost what we have now. We have to be very careful as the punters turn up to watch the BTCC because it is close and tight. What they don't want is to see a Formula One display from someone with a good car and a different type of car who can drive off into the distance. It isn't what the fans want."

Looking to the future, Harrison admitted that the diesel route wasn't one Vauxhall would be likely to follow because of the costs involved in developing the programme.

Indeed, he added that, while development of the 2009 VX Racing entry was already underway, he was unsure of how much can be done to match the current pace being set by arch rivals SEAT.

"We have been looking at next year's car for the last two months, and we have a programme that will start the week after Brands Hatch for next year," he said. "It is a bit of an issue as we are running out of things to modify to make our car better as year on year you make improvements, but as for making the big jump we need to make, I'm not sure we can to be honest. It will be a challenge, but I honestly don't know if it is doable, I really don't.

"We have looked at the diesel route and frankly for Vauxhall, it isn't affordable. Vauxhall do very well in the passenger car market because they are careful about how they spend their money and they run their business very tight. It shows because they do well and are profitable. They can't just start to throw a million pounds at a diesel programme when there should be an equivalency mechanism in the championship which allows everyone to compete against each other whether you are running diesel, petrol, gas or whatever.

"You shouldn't have to go and spend millions of pounds just to compete, it shouldn't be like that."