I drive a 4 cyl 2008 Camry. This is my third Camry, and I’ve never noticed this phenomena before. When accelerating from a stop, as soon as equilibrium is reached, whether it be 40mph or 55mph; the tachometer drops to 1500rpm. This probably helps with gas/mpg, but my question is “how does this work?” Am I getting better mpg @55 or at 40mph, or somewhere inbetween?
It is normal for rpm to level off after the car is no longer accelerating, I don’t get it.
I believe your car has a continuously variable transmission. If your shifter reads PRNDL instead of, say PRND321, it is a CVT. This would explain the same RPM at different speeds. Tom and Ray explain the CVT as being like a rubber band, which drives your wheels, being on a gearset that looks like an ice cream cone. The larger part of the cone gives you lots of torque to start, and the smaller end of the cone gives you an overdrive to provide gas mileage and highway cruising. Traditional transmissions used individual gear ratios whereas the ice cream cone shaped drive gives you an infinite range of ratios, allowing for optimal MPG and torque.
As far as the speed for the best gas mileage, you have to figure that out for yourself since all cars are different. Your mileage will increase to a point when the extra work the engine is doing is offset by the amount of wind resistance your car is pushing against, which increases with speed. Your mileage will taper off at some point. The point right before it tapers off would be your optimal speed.
Your gas mileage will decrease as speed increases. Cruising at 40 mph will result in better mileage than cruising at 55. And cruising at 55 will result in better mileage than cruising at 65, etc.
Does your Camry have a CVT (Continuously Variable Transmission)?
I Think Henry Is Saying 1500 RPM At 40MPH And 1500 RPM At 55MPH, How So?
CSA
Oh, well, yes; a CVT would explain it. Thank you mark9207.
I think only the Camry Hybrid has a CVT, not the regular 4cyl.
I don’t think this is a continuously variable xmission. The shifter reads PRN 4-D 3 2-L ---- 1500rpm will hold the speed constant anywhere between 40 and 55mph. Over that speed, the rpms jump to 2200+/- and that holds up to about 70. Very strange behaviour, and overall I’m not getting better mileage than my last 4cyl Camry. This seems to handle like a heavier car, however, and it is loaded with all the latest gimicks. 24mpg overall, 32 on a recent road trip.
Henry, Are You Sure The Tachometer Is Functioning Properly?
I’d run that one by a dealer. See if you can get a ride in a similar car, if need be, and see if “they all do that”. The “jump” part doesn’t sound right to me.
CSA
The Camry got a 5 speed auto in '05 (I think) so it has an extra gear compared to your other Camrys. You are experiencing either the lock up torque converter engaging and disengaging and perhaps a shift up to and down from 5th gear. The shifts must be so smooth that you see the change in the tach rather than feel the shifts.
When coasting on a slight decline you’ll see the rpm’s drop like this too. The tach will show the “jump” in rpm when the road inclines again as the motor has to provide power to maintain speed.
You have a 5 speed automatic transmission, not the CVT, unless it’s a hybrid. I suspect that you are in different gears and happen to be at the same RPM. But if your engine works as hard at 40 MPH and 55 MPH, you will get better mileage at 55 MPH.