1999 V70 T5 M mpg report - those painful 5mph above 60 mph

Post by **abscate** » 22 May 2015, 06:16

I made a trip to a local track meet with one of the kids last night and had to cruise the Taconic Parkway in NY. Thats a 55 mph road, crawling with NYSP, so I pegged the cruise at 60mph. 70 mph is both too fast and will get you a ticket.

Ive got 93 octane in the beast as Im towing boats, ambient temperature 60F

Lo and behold, in hilly country, my mpg jumped up from the typical 26mpg (cruise speed at 70mph) to 30.5mpg. On the trip back, I bumped up to 62 mpg and got 29.9mpg.

Looking at the tach, this speed is just before boost is coming on. This might be the sweet mpg spot for the High Pressure Turbo car.

Post by **tryingbe** » 22 May 2015, 11:04

Faster speed you go, the more energy you need to maintain that speed.
Speed limit was cap to 55mph in the 80's to maximize mpg.

http://kilowatt-age.com/yahoo_site_admi ... 01_std.png

Post by **precopster** » 22 May 2015, 15:11

My 5 speed NA non turbo sits at 2, 100 RPM at 62mph or 100kph. Drag co efficient of Volvos is not typically stated in literature these days. In the 80s manufacturers were just getting the hang of making "slippery" bodies.

The Subaru Vortex had a 0.29 drag co efficient which is very slick. I still urge for an AWD XT Turbo version but all of them are rusted out and in backyards as possum housing

Perhaps Jay Lenno has one??

What engine speed does the HPT do at this speed Steve?

Post by **j-dawg** » 23 May 2015, 15:19

Not Steve, but engine speed between a T5 and an NA car should be the same if the transmissions are the same. An M56H is an M56H.

Post by **precopster** » 23 May 2015, 15:54

My 5 speed is an auto so different final drive ratio.

Post by **j-dawg** » 24 May 2015, 00:25

Ah, whoops. I see.

Well, I took my T5M out tonight and was turning ~1600rpm at 40mph, so it should be 2400rpms at 60mph.

Incidentally, I did see one of those Vortices (we call them XTs here) the first time I drove my Volvo, when the previous owner picked me up from the bus station. Super cool cars. Subaru has lost a lot of its charming weirdness over the last few years.

Post by **abscate** » 27 May 2015, 04:57

62mph 2400 Rpm indicated.

I knew that pretty well from when my ABS was out and I had to use the tach as speedo

Post by **abscate** » 29 May 2015, 17:20

...and on the P2 the difference isn't as profound.

80-90F
93 octane
38 mpg at 60 mph
35.5 mpg at 70 mph

This P2 from Jim is insanely nice to drive and mid-30s fuel economy is just wrong....

Post by **precopster** » 29 May 2015, 17:30

I know the P2s are revving lower than P80s at any given speed but they are heavier. There is more at play here.

P80 wagons have a drag co efficient of 0.32

P2 wagons have 0.30 which is pretty awesome for such a wide and long vehicle.

Is your P2 a non turbo Steve?

Post by **abscate** » 29 May 2015, 18:57

NA, correct. It doesn't have the snap of the T5 but it's great fun to drive for mileage