Emilis is an old friend with whom I have shared many journeys – most often in sailplanes.
Here are some of his notes from this shared journey at ground level.
A 59 year old environmental architect based at Monarto in South Australia, where he has a 100 acre land revegetation site on which he built 25 years ago his self sufficient solar powered home office; who for near to 10 years has driven hybrids, and for 4 decades has flown sailplanes.
The common theme here is an abiding interest in effective resource use, in particular energy efficiency.
The sailplane mindset is to gain energy and use it appropriately in speed and direction to maximise flight.
His 2000 Prius has 230,000km with minimal repair cost and a lifetime 4.7 l/100km fuel use. His partner Rachel has a 2005 model, and is achieving 4.3 average with the same drive style.
The Tesla Roadster distance record drive of 27th October 2009 drew on these approaches to look to extract mileage during the drive.
Traditional wisdoms from fossil fuel cars are to hold steady direction and high gear and torque band optima.
Hypermile thinking more closely follows the sailplane mode of minimising energy loss and maximising effective work:
- speed is varied in line with (even minor) road elevation variation, looking to crest each peak with minimum ascent energy use, and maximise speed on downslopes at less than the speed at which aerodynamic losses rise.
- entering regen mode in the electric drive system is minimised
- position on the road is adjusted to seek the least rolling resistance
On the Alice Springs – Coober Pedy drive, sections paved with a smooth ‘hot mix’ surface offered almost 1kW less resistance than gravel topped bitumen segments. Alternate sections and road widening sections of different surface types were found along the stage.
Heavy trucks have dimpled the most used road travel line through the bitumen into the sub-grade. Less resistance was found on the unused road shoulder and its thick line marking paint.
Pot holes and imperfections were studiously avoided.
A varied line on the road width was therefore sought.
With the factory standard Tesla, none of the usual vehicle tweaks (thin high pressure LRR tyres, aero mods, etc.) were available on this trip.
Instead cruise control was used as a hand throttle to promote precise and gentle change speed control.
The result was high driver workload even at the modest speeds being used.
But with record distance results.