Driving the Prius 2010 on a German Autobahn...

I have been driving from Munich to Offenburg yesterday, via Stuttgart. All in all 370km/230mi (90% highway) in about 4,5hrs, avg. speed 80-85km/h-(50-52mph) as reported by the computer (I don't remember the exact value, sorry).

The traffic was really thick (Friday afternoon...) and because of the expansion of the Autobahn A8 from 2 to 3 lanes (yes, you read correctly, 3, not 6 or 7 - we are not there yet, but we are doing our best to copy the US, and filling those lanes with SUV like vehicles ). The whole of the A8 is hilly with steep declines (up to 6%) and inclines. There are simply no tunnels and it's all up and down...not many flat sections...

About 1hr of the whole driving time, was spent in stop&go traffic jams, mainly due to roadworks and heavy traffic. The rest of the time I was driving as fast as I could: after all I live in Germany, let's have fun sometimes and more over I wanted to see how the Prius was doing at high speeds.

When no speed limit was given (typically there is a 120km/h-75mph limit over a good third of the way and 80km/h-50mph one in all roadwork sections), I was going anything slower than 150km/h-93mph and as fast as 190km/h-118mph.
The overall stability was good but not excellent - I am driving now with winter tires (195/55 R16), instead of the 215/45 R17 - so this is certainly one limiting factor. I have tried driving 190km/h already once with the 215 summer tires and the stability is excellent.

Acceleration is OK but not that exciting - but mainly I was chased from 2.0+L BMWs/Mercedes and the such with 150+HP at least. I was never chased by a Golf or other mid-sized car. Surely the Prius is not a Ferrari, but you need to push it to get juice out of it (at least at these speeds). Often you press the gas and "nothing" happens. The eCVT likely doesn't help, but I cannot imagine shifting gears at these speeds, it doesn't make any sense - you really need HP and torque (if any left....).

The engine gets quite noisy and the HSI is no indication of what are the RPMs of the ICE and if you are melting it down The HSI bar might not be in the red PWR zone, you are doing 180km/h-111mph going uphill and the engine is roaring, but you have no clue whether you are in the red rpm zone.....
Comically enough, I never really had to floor the accelerator, but honestly I was afraid of having the ICE jump out of the car...

I used power mode all the time, not because the car goes any faster, but simply because on German highway, people do drive fast - no only in terms of overall speed, but also in terms of reaction times. When there is a chance to go faster, they will do it. No grannies here! So you need to accelerate fast, and PWR Mode gives you better reaction to the foot. After arriving in Offenburg I had to keep the PWR mode on as my foot got so used to it, that normal mode felt like ECO!!!

What I noticed is that the battery charges continuously - the ICE is running so much and at max power that it can generate traction power, power for the generator and power for the electric motor. The batter was charging while the motor was driving the wheels at the same time. This has been the only time that I have ever seen the battery of my Prius fully charged, even if for just a short period of time. Most of the time it was 70%-80% full.
Having a full battery was really helpful when stuck in a traffic jam or at lower speeds as I could coast in electric mode most of the time.

So now the main question is - what was the average fuel consumption, including 25km/15mi in town before leaving Munich????
10L/100km-23MPG? No. 8L/100km-29MPG? No. It was just 6L/100km-39MPG. I am honestly impressed. :jaw:
This also means that if I drive it more slowly (say 140km/h-87mph), I would probably get 5L/100km-47MPG. And that for a german autobahn *is* impressive. I would never get that on the Polo diesel I got before.

I have also tested today going 150km/h-93mph more or less constantly, and you do get 7L/100km-34mpg average.

A good reason for driving slower though, is to reduce the stress on the suspensions and overall on the drive train. German highway are indeed flat and quite good taken care of, but any tiny bump at these speeds is truly heavy on the suspensions. The last thing I want is to change something in 4-5 years time due to fast driving. I wonder if I have not already compromised some mechanical part (I am already imagining cracks and mini-fissures crawling up metal parts in the suspensions.... my poor Prius!)

I will drive back this Sunday I will post my findings on this thread.

So, overall good, not a Ferrari and certainly not an "easy/comfortable" german highway car. On more relaxed highway trips though (140km/h max), it is certainly a good comfort car with (likely) excellent fuel consumption especially if helped by some traffic jams...

 

The Polo was a turbodiesel, 1.4L with 75HP and weighing 200kg less.
Diesel are *extremely* efficient in constant speed, 90-100km/h driving. You start to go fast and consumption goes up.
Although I drove the same road with the Polo I don't remember the average fuel consumption I have achieved. If it were the same, it would be a true accomplishment for Toyota.
But I do have written down the instantaneous fuel consumption of the Polo at different speeds on flat or nearly flat highway (as precise as I could be - there are not so many flat roads around where I live):
80km/h 3,9L/100km
100km/h 4,9L/100km
120km/h 6,2L/100km
150km/h 7L/100km
170km/h 8L/100km

Essentially the Prius consumes the same at the same speeds, from what I manage to see. Considering the 18% extra weight, the 81% more HP, the 23% more torque and the 26% bigger engine, while accelerating from 0 to 100km/h in -24% time (10,4 vs 13,6) and producing -24% less CO2, nothing to complain about here...

 

So today I drove back, not doing the same road as I was leaving from Freiburg and the route via Memmingen/Ravensburg was shorter and more scenic. 345km/214mi in total, 202km/125mi of which highway. I drove mostly not any faster 140km/h-87mph apart a few cases in which I drove up to 180km/h-112mph for less than 1 min.

The road from Freiburg till the first stretch of highway is uphill, the rest is up&down, up&down, repeat...

Going uphill, the consumption was 7L/100km-34mpg, the rest was around 5L/100km-47mpg or less. Hence the average of 5.2/100km-45mpg (see image attached).

A few short stretches of road were in town/villages (no more than 50km/h-31mph) and the rest on country side roads (between 70km/h-44mph to 100km/h-62mph). Lots of braking (not to a stop) and speeding up again. Lots.

The overall avg speed is 90km/h-56mph, so I wasn't really driving like a granny.

Is 5.2L/100km-45mpg good enough?


FYI - elevations:
Freiburg 278m - starting point
Titisee 845m
Neustadt 849m
Ravensburg 450m
Memmingen 601m
München 519m - end

As you see...up&down&up&down. To get a flat stretch of road around here....you need to drive to Holland!! No wonder I could not do 4L/100km-59mpg!!!!

PS: I noticed a difference between PWR and normal mode, apart from the accelerator mapping. When releasing the accelerator in PWR mode, the engine tends to remain engaged although not consuming any fuel. If I pressed the PWR mode to disable it, I could clearly notice the ICE disengaging. Why does the ICE remain "on", though not been fed gas, when releasing the gas (gliding) - the speed at which this happens is around 100km/h-62mph.
PS2: just to clarify - all posted speeds in my posts, are allowed by the law. Unless otherwise noted, on german highways you are allowed to drive as fast as you can, as long as you keep enough distance between you and the car that precedes you. Country roads have a speed limit of 100km/h and in town, 50km/h. All these speeds are limited according to road type, tunnels, etc.

 

Today I did 193km/h - that's 120mph. But... that is what the speedometer is telling and not the real actual speed. With the use of a friend's GPS I have found that you need to drive 66km/h to get 60km/h real (10% margin; that is with 17" wheels). If the error is constant, above a certain speed that is, then 193-10%=175km/h. Which means that if the declared speed limit is 180km/h, you need to see 198 displayed to really be at 180km/h.
I had to brake today when I saw 193, and the Prius wasn't finished quite yet - I know I could have gone up a tad more. So 198km/h might well be the max speed you can see on the speedometer. And I am pretty sure a 200km/h cannot be physically be displayed in the current dashboard anyways (as far as I can see, there is no "2" available...)