<p>Tesla Inc's attempts to humble Porsche with a new lap record on Germany's legendary Nordschleife racetrack have reignited a controversy about the value of lap times, as the circuit steps in to quash claims of cheating.</p>.<p>Porsche and U.S.-based Tesla are battling to establish supremacy in lap times for four-door electric sportscars, but comparisons are not exact, as conditions, ranging from car modifications to tyre types, vary with each test.</p>.<p>"We want to have circumstances that can be understood and replicated," said Nuerburgring spokesman Alexander Gerhard, adding that the racing circuit operator had moved to tighten rules by which a carmaker can claim a certified lap time.</p>.<p>Setting a new record time for four-door electric cars would give Tesla's ageing Model S a boost just as German rivals Audi, Mercedes-Benz, BMW and Porsche prepare to launch their own electric cars.</p>.<p>Automakers use the Nordschleife, one of the world's most treacherous courses with 40 right-hand and 33 left-hand turns, to hone a vehicle's sporting characteristics and burnish a car's image for marketing purposes.</p>.<p>Tesla was spotted this week with a variant of its Model S sedan at the circuit, which is 20.8 km (12.9 miles) long, with slanted cambers and a 300-m altitude difference between its highest and lowest points.</p>.<p>German car magazine Auto Motor und Sport said a Tesla was seen recording an unofficial time of 7 minutes and 23 seconds, which would beat a lap time set by Porsche's Taycan, which Porsche says achieved a lap time of 7 minutes and 42 seconds.</p>.<p>But Tesla's challenge has prompted questions about whether the Silicon Valley car maker is playing fair.</p>.<p>"The car was heavily modified," said Stefan Baldauf, who photographs prototype vehicles being tested on the circuit for a living.</p>.<p>"Aside from a roll cage and the driver's seat, the interior had been stripped out," he added. "The windows were blacked out, so it was hard to tell."</p>.<p>The Tesla also appeared to have semi-slick tyres, used only on racing circuits and unsuited for everyday use, Baldauf said.</p>.<p>A Porsche spokeswoman told Reuters its Taycan was tested using standard tyres.</p>.<p>"A comparison is hardly fair if this is the vehicle used to demonstrate that Tesla is faster," Baldauf added.</p>.<p>Notary Jens Boehle, who certified lap times by Porsche, said, "Scope for cheating is as big as you can imagine. Is it a prototype vehicle, a standard road-legal vehicle, or is it a specially modified racing version of a standard road car?"</p>.<p>"These are just some of the questions that need to be answered."</p>.<p>Tesla Chief Executive Elon Musk responded on Twitter this week.</p>.<p>"The final configuration used at Nürburgring to set the record will go into production around summer 2020, so this is not merely for the track," Musk said.</p>.<p>Tesla declined to comment on its lap record effort.</p>.<p>Officials are trying to standardise speed record attempts, Gerhard, the Nuerburgring spokesman, said. In some runs for the record, cars were allowed to make a flying start using a 20.6-km (12.8-mile) stretch of the track.</p>.<p>"We now mandate that the full 20.8 km is used," Gerhard added. "And we employ a notary to measure the time following rumours that another manufacturer had cheated, by speeding up video footage."</p>.<p>It also mandates where timing devices should be located.</p>.<p>On Twitter, Musk confirmed that Tesla is using the Nordschleife to market its "Plaid" mode on a 7-seater Tesla Model S.</p>.<p>"We expect these track times to be beaten by the actual production 7 seat Model S Plaid variant that goes into production around Oct/Nov next year," Musk said.</p>.<p>Porsche says its 919 Evo hybrid racecar now holds the overall record for all vehicle categories, with a lap time of 5 minutes and 19 seconds, set in 2018.</p>.<p>Nuerburgring hopes the new rules, introduced this year, will help revive the circuit's popularity as a venue for competitive benchmarking.</p>.<p>"We want to be a believable benchmark," Gerhard said.</p>
<p>Tesla Inc's attempts to humble Porsche with a new lap record on Germany's legendary Nordschleife racetrack have reignited a controversy about the value of lap times, as the circuit steps in to quash claims of cheating.</p>.<p>Porsche and U.S.-based Tesla are battling to establish supremacy in lap times for four-door electric sportscars, but comparisons are not exact, as conditions, ranging from car modifications to tyre types, vary with each test.</p>.<p>"We want to have circumstances that can be understood and replicated," said Nuerburgring spokesman Alexander Gerhard, adding that the racing circuit operator had moved to tighten rules by which a carmaker can claim a certified lap time.</p>.<p>Setting a new record time for four-door electric cars would give Tesla's ageing Model S a boost just as German rivals Audi, Mercedes-Benz, BMW and Porsche prepare to launch their own electric cars.</p>.<p>Automakers use the Nordschleife, one of the world's most treacherous courses with 40 right-hand and 33 left-hand turns, to hone a vehicle's sporting characteristics and burnish a car's image for marketing purposes.</p>.<p>Tesla was spotted this week with a variant of its Model S sedan at the circuit, which is 20.8 km (12.9 miles) long, with slanted cambers and a 300-m altitude difference between its highest and lowest points.</p>.<p>German car magazine Auto Motor und Sport said a Tesla was seen recording an unofficial time of 7 minutes and 23 seconds, which would beat a lap time set by Porsche's Taycan, which Porsche says achieved a lap time of 7 minutes and 42 seconds.</p>.<p>But Tesla's challenge has prompted questions about whether the Silicon Valley car maker is playing fair.</p>.<p>"The car was heavily modified," said Stefan Baldauf, who photographs prototype vehicles being tested on the circuit for a living.</p>.<p>"Aside from a roll cage and the driver's seat, the interior had been stripped out," he added. "The windows were blacked out, so it was hard to tell."</p>.<p>The Tesla also appeared to have semi-slick tyres, used only on racing circuits and unsuited for everyday use, Baldauf said.</p>.<p>A Porsche spokeswoman told Reuters its Taycan was tested using standard tyres.</p>.<p>"A comparison is hardly fair if this is the vehicle used to demonstrate that Tesla is faster," Baldauf added.</p>.<p>Notary Jens Boehle, who certified lap times by Porsche, said, "Scope for cheating is as big as you can imagine. Is it a prototype vehicle, a standard road-legal vehicle, or is it a specially modified racing version of a standard road car?"</p>.<p>"These are just some of the questions that need to be answered."</p>.<p>Tesla Chief Executive Elon Musk responded on Twitter this week.</p>.<p>"The final configuration used at Nürburgring to set the record will go into production around summer 2020, so this is not merely for the track," Musk said.</p>.<p>Tesla declined to comment on its lap record effort.</p>.<p>Officials are trying to standardise speed record attempts, Gerhard, the Nuerburgring spokesman, said. In some runs for the record, cars were allowed to make a flying start using a 20.6-km (12.8-mile) stretch of the track.</p>.<p>"We now mandate that the full 20.8 km is used," Gerhard added. "And we employ a notary to measure the time following rumours that another manufacturer had cheated, by speeding up video footage."</p>.<p>It also mandates where timing devices should be located.</p>.<p>On Twitter, Musk confirmed that Tesla is using the Nordschleife to market its "Plaid" mode on a 7-seater Tesla Model S.</p>.<p>"We expect these track times to be beaten by the actual production 7 seat Model S Plaid variant that goes into production around Oct/Nov next year," Musk said.</p>.<p>Porsche says its 919 Evo hybrid racecar now holds the overall record for all vehicle categories, with a lap time of 5 minutes and 19 seconds, set in 2018.</p>.<p>Nuerburgring hopes the new rules, introduced this year, will help revive the circuit's popularity as a venue for competitive benchmarking.</p>.<p>"We want to be a believable benchmark," Gerhard said.</p>