The arugments about i3 vs Tesla are all irrelevant anyway. The Tesla costs almost double the cost of an i3 rex. Efficiency is more than Wh/mile, its also £/mile. And the i3 works out cheaper per mile due to having a lower purchase price and hence depreciation costs. The high price also affects the fact that probably 10 times as many people can afford an i3 than a Telsa. That's judging by the number of £30-40,000 cars on the road(A4/3 series/C class etc) , Vs £50,000+ cars(V8 Luxury cars/performance cars). So overall the i3 will have a bigger impact on reducing emissions. But I'd still prefer a Telsa when I can afford one ;-)
Back to the original question about shortest journey time... Given the REX is an ICE and they are most efficienct at maximum power (as the throttle is wide open and not creating a vacuum) it might be feasible that driving as fast as possible for short bursts with Maintian SOC on, then dropping back to reduce drag and stop the battery depleting while the REX is still running flat out for a bit as it catches up to where it should be. That's based on the assumption if you set it at 75%, then it drops to 65% it will keep generating flat out till it reaches 75%. - mine's not due till March 2015 so can't try it out. :-( Once you get back to 75% SOC hit the gas, er, I mean electron pedal. Do you get any indication of what the REX is doing other than how loud it hums? Like revs, or power output gauge?
That's quite hard to model - even for me and I'm an excel whizz.
[edit to add...]
I forgot to say 7 minutes for a fill up? You obviously don't have a 20 litre jerry can
That's 7 minutes every 3rd stop, and 1 minutes 50 seconds for the other 2.
15 to get out the car and open the hatch
15 to get the can and open the fuel flap
50 seconds pouring (maybe less)
15 to put can back
15 to get back in the car.
;-)
The question now is do you make a stop to use the last 2 liters in the jerry can? Probably, for 1m50 you get 20 more miles. Call it your fuel station finding reserve after you run the rex dry for the 3rd time in a row.
What you really need is a roof rack with 4 jerry cans, all linked to a gravity fed auto filler upper that replaces the standard fuel flap. sod the aero, you want to get there fast. It's what the guys doing long distance overland trips do when doing things like trying to set the London to Cape Town records.
http://www.4x4lifestyleshop.com/shop-equipment/expedition-accessories/fuel-tanks/90-aux-fuel-tank.html
Hmmmn... there's an idea.