Thrifty but tardy: Goodyear-shod Prius sets Nürburgring record

Toyota may well have broken two records at the Nürburgring circuit in Germany, and is keen to share details of one of them. A modified, Goodyear-shod Prius has recorded the most fuel-efficient lap of the Nordschliefe. It was perhaps also the slowest lap officially recorded by a vehicle manufacturer.

The company’s aim was to see how little fuel it could use on a single lap of the Nordschliefe. The car Toyota brought to the Nürburgring was a Prius Plug-in upgraded with the addition of TRD parts, however Toyota says these changes were styling elements that improved the car’s appearance rather its fuel-efficiency. Nevertheless, the standard 6×15 Prius Plug-in alloy wheels and 195/65 R15 tyres were substituted for 7.5×18 rims and 225/40 R18 92W tyres. “We knew it would not be necessary to buy tyres with a super-sticky compound that would deliver a dramatic increase in grip at the expense of a decrease in fuel economy,” commented driver and journalist Joe Clifford in Toyota’s blog about the project. “Instead, we studied the new coding regulations and bought a set of Goodyear EfficientGrip Performance tyres with the lowest possible rolling resistance, lowest noise production and most efficient water dispersion characteristics.”

On paper, both the circuit’s 60km/h minimum average speed requirement and its length of 12.9 miles put the feat within the all-electric EV range Toyota quotes for Prius Plug-in, and in theory the distance could be covered without a drop of petrol being used. In dry, breezy conditions, Clifford recorded 698mpg and completed his Nordschliefe lap in 20 minutes and 59 seconds. This performance far outstrips the car’s official combined cycle figure of 134mpg, and Toyota says the car used less than five tablespoons of fuel to do the job. On the minus side, the lap took a hair under five minutes longer to complete than that of the previous wooden spoon holder, a 20hp East German Trabant P50 from the VEB Sachsenring team, which recorded a 16:01 time at the circuit in April 1960.

The technology that made this fuel-efficiency feat possible is a development of Toyota’s full hybrid system that matches a 1.8-litre Atkinson cycle petrol engine with a compact, rechargeable lithium-ion battery. The battery’s performance and excellent energy density means the car can be driven further and at higher speeds on electric power alone than the standard Prius.

“We used no special tricks for this test. We simply took a fully charged car, fitted it with low rolling resistance tyres and drove the lap, among all the other public drivers taking the opportunity to experience the challenge of the Nürburgring,” said Clifford. “Although the 12.9-mile distance is similar to a typical commuter trip, the difference here is a rise and fall in elevation of around 1,000 feet. In fact it was only on one long climb that the petrol engine cut in, and then only for a short while. Without that, we think we might have even achieved the ultimate 999.9mpg read-out – the highest figure the display can show.”