2007 Boxster 987 3.4s manual - poor fuel consumption.
Discussion
For comparison. Just been touring on the continent in 981 S Cayman (PDK - so high gearing in 7th helps). Mostly motorway stuff, and above 70 - averaged 35 overall. Only one real chance to cruise at 3 figures on German Autobahn - got an astonishing (I thought) 33mpg, but it was one way so may have been wind assisted. I'd expect around 38mpg at 70. I also did brim to brim checks and the figures the computer gave were pretty much spot on.
I don't trust the mpg display on mine at all.
The other day, I reset it and drove about 10 miles in town traffic before I got on the M25. When I got onto the motorway it read 19mpg, when I got off 25 miles later it was on 21.
On the way back, I reset it as I got on the motorway and did the same route, again cruising at exactly 70mph through the camera zone. This time 35mpg.
Unless my maths is wrong, 10 miles at 19mpg and 25 miles at 35mpg should average out at over 30mpg, not 21.
I realise that this is not a scientific test, but it is a long way out. The other thing that annoys me is that it doesn't change at all after a while. I don't use it all that often, and I went through 2 tanks of petrol with it stuck on 24.6mpg regardless of how I was driving.
The other day, I reset it and drove about 10 miles in town traffic before I got on the M25. When I got onto the motorway it read 19mpg, when I got off 25 miles later it was on 21.
On the way back, I reset it as I got on the motorway and did the same route, again cruising at exactly 70mph through the camera zone. This time 35mpg.
Unless my maths is wrong, 10 miles at 19mpg and 25 miles at 35mpg should average out at over 30mpg, not 21.
I realise that this is not a scientific test, but it is a long way out. The other thing that annoys me is that it doesn't change at all after a while. I don't use it all that often, and I went through 2 tanks of petrol with it stuck on 24.6mpg regardless of how I was driving.
I have a 981 Boxster S with PDK. Got back this week from 1800 mile French trip, averaged just over 39mpg. Admittedly mainly main roads and sticking fairly closely to the speed limits. The use of the glide facility aids consumption a lot. You can glide for a mile or two on some downhill sections. Nothing special about my car; give it the beans on a back road and it's in to the low twenties. Oh, that consumption is 95% hood down. Had to put it up for torrential rain for half an hour and when it hit 34 degrees one day and threatened to burn my wife and I to a crisp.
I have a 981 Boxster S with PDK. Got back this week from 1800 mile French trip, averaged just over 39mpg. Admittedly mainly main roads and sticking fairly closely to the speed limits. The use of the glide facility aids consumption a lot. You can glide for a mile or two on some downhill sections. Nothing special about my car; give it the beans on a back road and it's in to the low twenties. Oh, that consumption is 95% hood down. Had to put it up for torrential rain for half an hour and when it hit 34 degrees one day and threatened to burn my wife and I to a crisp.
OldChap said:
I have a 981 Boxster S with PDK. Got back this week from 1800 mile French trip, averaged just over 39mpg. Admittedly mainly main roads and sticking fairly closely to the speed limits. The use of the glide facility aids consumption a lot. You can glide for a mile or two on some downhill sections. Nothing special about my car; give it the beans on a back road and it's in to the low twenties. Oh, that consumption is 95% hood down. Had to put it up for torrential rain for half an hour and when it hit 34 degrees one day and threatened to burn my wife and I to a crisp.
As you say the glide function does seem very effective. All that said and accepting that the 981 pdk is going to be significantly better than a 987 manual, 22 does seem very poor. I haven't seen figures for the extra aerodynamic drag on a Boxster with the the hood down - but I would guess at somewhere around 20% mark, perhaps a bit more. The increase in fuel consumption would be less than that because at modest speeds friction and tyre drag are still significant. So I'm still surprised if there isn't something wrong with the car - even if it's only an inaccurate fuel computer.Gassing Station | Boxster/Cayman | Top of Page | What's New | My Stuff