Can a Porsche 911 do 40mpg if you hypermile it?
Eco-driving. You get into a rhythm after a while. Build speed gently, predict traffic flow, coast where you can. But why bother? You’ve got a Porsche 911, just go ahead and use it, get that flat six singing, surely? Well, yeah, but it’s always interesting to try new things. And yes, I know ‘fun’ is the usual word to throw into that sentence, but eco-driving is type two fun.
Anyway, the reason for it was that over the first two months with the car I’d covered about 2,500 miles doing all sorts of stuff, a lot of it with bikes on the roof, and yet the 911 had averaged 29mpg overall (about 26mpg with bikes on top, 32 or more running as bald as its driver). That struck me as good.
I was driving as I wanted to and still beating the WLTP figure of 27.4mpg. I was getting nearly 400 miles from a tankful. This is a very quick sports car and yet looking back at other cars I’ve run it was more efficient than a Toyota GR Yaris (27mpg), vastly better than an Audi RS6 (22mpg) and on a par with the last two diesel Land Rovers I’ve had – a Velar D300 and Disco 5 TD6 (29 and 27mpg respectively).
Oh, and if you’ve got one of those and it’s telling you you’re doing 32mpg or something, know that the trip computers are over ten per cent out.
The type of driving is broadly the same: for obvious reasons I’m not commuting in and out of London like I used to, but the majority of the miles are racked up heading to locations at least an hour from home. Motorway slogs were exactly that in the Yaris, which was brilliantly short-geared for back country smashing about, but had the rev needle (and my ears) busily buzzing on multi-laners.
The 911 pulls 1,600rpm at 70mph. Not very sporty? No need, there are seven other gears to play with, so having one that’s geared like a pair of seven-league boots is entirely fair enough. Long story short, I reckoned with a bit of self-discipline I could get the 911 to cover over 500 miles between fill-ups.
No change in my routine and – more importantly – no extreme measures. Slipstreaming trucks, turning off the AC and holding up other traffic were strict no-nos. Just look further ahead and see how it got on.
Result: 518 miles on 64.74 litres of fuel for an average of 36.37mpg. The trip meter said 37.0mpg, a deviation of 1.72 per cent. I’m actually slightly disappointed by that, because at one stage it looked like I was destined for over 550 miles after one wind-assisted M4 drive back from Wales topped 40mpg.
Still, that’s a 25 per cent uplift in fuel economy from not really enjoying the car. And feeling slightly ashamed. Especially that time a Fiesta ST caught me doing 50mph on the B4009 and came razzing past, driver shaking their head. Nearly caved in right there and then.
It’s been instructive. Other road users have been suspicious: ‘why is that 911 dawdling at 69mph in the inside lane?’ you can sense them thinking; ‘what’s he spotted that we haven’t?’. Maintaining speed around bends on country roads has been fun, but not downshifting and accelerating out has been tedious.
This is already probably the dullest sounding flat six ever to have been fitted to a Porsche, and all I’ve had is ten days of low rev droning from it.
Now I think about it, although I have hard evidence the 911 is way more efficient than the WLTP test says and that it is possible to cover over 500 miles on more fuel than you should be able to get into a 64-litre tank (tip: the range indicator changes to three dashes when you have about 10 miles of range left. Take it at face value), I think it’s potentially more impressive how efficient the 911 has been when I’ve been driving it as I wanted to. It’s proof of how thoroughly engineered the car is.
When the 911 switched to turbocharging a few years back I was sceptical. Turbocharging might improve efficiency in lab tests, but in the real world it never seemed to. But I don’t think I’d ever be able to coax 37mpg out of a nat-asp flat six. Do you know different? I’d be interested to find out. However, I don’t think I’d have been able to sustain an economy run in the old one. The noise and response would have undermined my pitiful self-discipline.
One final thing. In left-hand drive markets you can order the 911 with a long range tank. It’s only something like 150 euros to upgrade from 64 litres to 90.
At 36mpg that’s a potential range of 728 miles. Glad I didn’t have to hold on for another 200 miles.