Been lucky enough to be allowed to drive the wife's '13 ES350 to the grandson's baseball games this year and it takes us about 90 minutes to travel to the games, and we travel the interstates to get there. When the CC is set at 69 or so, or any speed really, when going down a somewhat steep hill (live near Knoxville TN), the CC holds the speed close to the set speed, but noticed the tach jumping around due to engine braking when going down hill. The tach hit 3K last night coming home, speed was set at 69/70 mph on a downhill turn due to engine braking. Using the ECO mode on the tranny 100% of the time.

Just wondering if this is normal in the ES350 as no other vehicle I've owned has reacted to this degree/extent while not towing a boat or RV.

 

Seems normal. If it didn't engine brake, it would keep speeding up.

 

I noticed the same thing the last couple of weeks when I drove out to the West Coast and back. The “reality show” Highway Thru Hell”, otherwise known as the Coquihalla Highway, has a speed limit of 120 kph (73 mph) so 130/80 is where the cruise control got set. It is a high elevation highway with a lot of very long grades and the ES (which you know is slippery as an eel and coasts like a rocket) really tries to pick up speed on the downhills. I saw the fuel consumption meter pop up to 8-10 litres/100 km while the rpm kicked up to about 3000. I tried popping it into “manual” and selecting 6th gear and that seemed to drop the rpm back to about 2000 and, more importantly, the consumption meter down to close to 0 l/100 km. I don’t know what measures are input to generate the fuel consumption reading but it seems engine rpm is an important one rather than just vacuum or fuel flow.

I “hard measured” (pump meter readings) gas consumption at 36.5 miles/Imp. Gal. (30 miles/US Gal) for this portion of the trip both ways so I’m really impressed with the overall efficiency of the 350 when driven fairly hard. Cruising at a steady 110 kph (67 mph) on the flat/ no wind/no acceleration for 80 miles got the short term average showing 6.9 l/ 100 km or 35 m/US Gal.

 

This is very normal and smart.Keeps your brakes from getting to hot and failing.

 

how in the heck are you getting over 30 mpg????????

best i managed by gliding + driving it 50-60 mph was about 27, and this is pure highway no stop and go, no slowing down and accelerating again. just constant 50-60 mpg not even changing lanes.

granted i'm 230 lbs, maybe my weight is dragging the car down? haah, i don't know

 

Well, maybe your extra 10 lb is heavier :-) ! (I am 220). Had my wife with me and a trunk full of stuff to take to my daughter plus our personals for 10 days so probably a total load of around 470-500 lb.

Here're my readings: you'll have to convert Imperial to US gallons by dividing by 1.2. Same for mpg. That last fill was including a top-up part way home so although the tank will hold about 65 litres, I'd never push it that far. The higher consumption rates are mostly in town/city with short stop-and-go hops of about 10 miles or much less. All 87 oct. gas with one fill of 10% ethanol (hate that stuff, priced the same but less energy content). Sorry for mixing up the units of measure...I was trained under the old system and Canada was just in the process of switching to metric while I was getting my engineering degree. Just wish I had the same facility for languages!

Edit: there is an error: the last "Overall litres/100 km" should read 8.09 instead of 3.68 and overall litres since purchase read 365.97 instead of 166.46. Blame the way I cut a portion of the spreadsheet out.

 

>getting over 30 mpg
Imperial gallons...
=================================
My karma just ran over your dogma
Current Hers: '13 Lexus ES350
Current Mine: '15 Jaguar XF (its aubergine)

 

Its completely normal most all current modern cars do this with CC. They also use the ABS solenoid to use the brakes much as its done for the collision avoidance/adaptive radar CC.

As for the huge variation we see reported in mpg for all car models of every make it has many actors.

1: Proper measuring which means fill tank up till its at the top of the fill neck to ensure a consistent start point. using the auto cut off even on the same pump can be off by over a gallon on fill-up consistency.

2: Tire condition and pressure. Old bald tires and high pressure filled tires get the best mileage compared to new full tread and air filled for max tread to ground contact.

3: Driving habits and use of Cc and the brake. Some people are automatic in timing lights traffic slow down etc to where they almost never use the brake and risk over limits speeds down hill to save momentum. Some people do all this out of habit.

4: the topology of where you live and commute is HUGE. If I am in Kansas I am getting way way better mpg than someone in the foothills in Colorado, Utah, or even where I live in the Shenandoah Valley region of Appalachia chain. I get 5+ mpg better hwy economy once I hit I10 going to Tx than I do going thru Tn Ky Va. Consider I can get 22mpg in Tx with my 7.3 PS diesel in my 8000lb+ Excursion if I am cruising @ 65. But here in Winchester Va its 18 and 14-17 combo depending on my foot.

5: use or non use of electrical and belt drive accessories. AC compressor and anything using the power generation of the alternator. Run your AC seat vent, radio cranked up at night with you highbeams on and you will use more than if those things were off.

 

Car had the exact same reactions today on the same road/interstate/downhill curve, so.... Thought it was normal but since I don't get to drive the car that much, LOL.

Car does not have adaptive CC. Open road in front of car, or least no traffic/cars that would require me to brake in the circumstances mentioned in my post.

We, well I do anyways get 30mpg cruising at 69/70 on the interstate here in E TN on a consistent basis. Wife kills the mpg's with her jackrabbit starts and sliding to a stop (think Nascar pit stops) when she drives the car but she still thinks she needs to drive from the passenger side whenever I drive. LOL