darth62

Anybody have a guess as to why the SH-AWD TL gets better MPG than the RL? I would have thought the two vehicles would offer very similar economy since they're likely to be very close in weight and power.

KeithL

Not sure what the numbers are, but the video explained that the TL has an electric power steering whihc gained them over .5 MPG and I forget what else they mentioend that got them a few tenths MPG.

darth62

Good point! I forgot about the EPS.

iforyou

iTrader: (1)

As you can see most of the gain is on the hwy (25 vs 22mpg). According to Jeff at TOV, the 5th gear on the new TL is very tall, like 0.491:1. I'm not sure about the RL but it's probably not as tall. And I believe there's still a 100-200lb difference between the 09 RL and 09 TL SH-AWD.

Colin

TL Tech SH-AWD is 3986 and the RL Tech is 4110. The Base RL is a litle lighter at 4083. Interestingly the RL has a carbon fiber driveshaft, aluminum subframes for the front and rear suspension, aluminum suspension arms, aluminum hood, fenders (front) and trunklid.

I haven't seen how much beyond the hood on the new TL is aluminum, but it seems like they are going with high strength steel instead. So despite being larger, and apparently using less exotic materials, it weighs slightly less. I don't know what this factoid says, but it is interesting.

edit: the RL top gear is the same 0.491.... Maybe the TL has better aerodynamics with the interior frame rails?

Costco

150 lbs can't make that much of a difference.... especially if both cars have the same final drive

darth62

Might it have anything to do with differences in the SH-AWD systems?

I have to say that, if the RL got the same fuel economy as the TL, I'd probably be driving one now.

csmeance

my guess is the drive-terrain loss. The RL has 35% loss, maybe the TL has less of a loss so more power to the ground means less RPM's needed to go the same speed.

Edward'TLS

Tall gear is bad. It means the car has no power at highway speed. The tranny has to kick down all the time for the car to accelerate.

Colin

LOL with only 5 gears, it doesn't have to kick down too many....

iforyou

iTrader: (1)

interesting topic..