World Touring Car Championship leader Gabriele Tarquini has questioned BMW's insistence that they have a diesel 320si, complete with a one second advantage over its petrol counterpart, waiting in the wings.
SEAT's diesel powered Leon has caused a wealth of controversy since its surprise debut at Anderstorp last season, after which the Spanish car quickly became a race winner and very nearly went on to snatch the title off Andy Priaulx.
However, despite missing out on last year's crown, SEAT are going the right way about avenging that this season, winning seven of this year's 14 races, results that see them lock out the top three in the driver's championship and command a 37 point lead in the manufacturer standings.
Their superiority has raised questions about the advantage the Leon TDI appears to have over the competition, not least from arch-rivals BMW, who went as far as building their own diesel-powered 320si during the winter period.
However, despite the German manufacturer claiming they had developed it into being one second faster than the regular BMW, it has never turned a wheel in competitive anger.
This leads SEAT's Tarquini to believe the advantage was not as prolific as they made out, possibly in a bid to spark the series organisers into action over reining the Leon in.
“The rules have been there since three years ago,” he told Crash.net Radio
. “No-one has built a diesel car before and it is not easy to build a fast diesel car. BMW announced their diesel car was one second faster than the petrol car, but while they homologated the car it is not here, so it seems that it was not one second faster. It was just a strategy to stop the diesel.
“They have a really good road car diesel engine and at the end of the season they may enter the car, but it is not as easy as everyone thinks. You have to work on the balance and set-up, but SEAT had this idea before everybody else, so they have spent a lot of time and money on this car.
“So now the question is not to stop the diesel, but to balance the performance. We aren't very happy about the last rules, because everyone had a performance waiver and the only car under the rules is the SEAT.”
However, BMW driver Jorg Muller, who tested the car earlier in the season, is adamant the car is considerably quicker than its petrol counterpart, but adds that the team are aware of moving the goalposts to the point that other manufacturers – like Chevrolet, who don't market a diesel Lacetti saloon - could pull out, or prevent others from entering.
“Personally, as a driver, I would like BMW to enter it because I know it is faster. On the other hand though, it could ruin the championship if only diesels can run at the front. Chevrolet doesn't have a diesel, Honda doesn't have a diesel... and we want more and more manufacturers coming in. The 2.0-litre normally aspirated engine is the right direction.”