Driving the Panamera on the Highway

The other day, I had some errands in Nagoya on a weekday, so I decided to drive my Panamera from home to Nagoya using the highway. However, since I had the impression that the Meishin and Shin-Meishin Expressways are often crowded with trucks and cars, I thought, “Maybe it would be easier to drive using ACC (Adaptive Cruise Control) the whole way.”

Since I was at it, I thought it might be interesting to “drive normally on the way there, then use ACC on the way back, and compare the fuel efficiency.” It’s commonly said that ACC, which keeps the accelerator steady, generally improves fuel economy, but I wondered how true that really is.

That said, the uphill and downhill sections on the outbound and return routes differ slightly, so it won’t be a perfectly accurate comparison… but I figured it was worth a try.

First, driving myself

When I set the navigation for the outbound trip, the fastest route—taking about two and a half hours—was “Meishin Expressway → Shin-Meishin Expressway → Higashi-Meihan Expressway → Nagoya Expressway Ring Route.” So I took that route.

For this drive, I focused on:

・Cruising at a steady speed without speeding or braking unnecessarily
・Staying in the driving lane when traffic was light, and overtaking with gentle acceleration

(Well, that’s obvious, but I hadn’t really been conscious of it before.)

I set off, but the local roads from home to the Meishin Expressway were always congested, which hurt the fuel efficiency quite a bit. However, once on the highway, the drive was relatively smooth. I didn’t take any breaks and arrived in Nagoya in just under two and a half hours as planned.

At this point, the fuel consumption read “8.3L/100km (my husband always sets it to European units),” which means about 12 km/L.

That’s really good!

Usually, on long trips in the Panamera, fuel efficiency tends to be between 9.0 and 10 km/L, so this was quite impressive. After arriving in Nagoya, I had a bit of trouble finding parking near my destination but eventually found an indoor underground garage and parked the car.

…But I completely forgot to take a photo of the fuel gauge before turning off the engine and heading upstairs. Too late.

Oops… (；ﾟДﾟ)(Lost the proof…)

I only remember the fuel consumption, so I don’t know the average speed, but I’m pretty sure it stayed at 8.3L/100km until the end.

Now, heading home with ACC

After finishing my errands, I set the same route for the return trip and set off. Traffic wasn’t too heavy, but there were quite a few cars. I thought, “This is definitely a job for ACC.” As I just held the wheel without doing much else, a strong wave of sleepiness hit me after about an hour and a half, so I stopped at Otsu SA for a short break.

Even with ACC, you can’t just fall asleep… (-_-)

Also, I completely forgot to buy souvenirs for the kids in Nagoya, so I went inside to look around—and to my surprise, among the Kyoto and Shiga souvenirs, there were actually some Nagoya souvenirs! Phew.

After buying the souvenirs, I continued the journey home.

The section near Kyoto Higashi narrowed to two lanes and got a bit congested, but after passing Kyoto Minami, it opened to three lanes and traffic flowed smoothly. However, near the Nishinomiya IC on the Meishin Expressway, there was lane restriction and traffic came to a complete stop, crawling along slowly.

At times like this, ACC really proves its worth. Fortunately, the traffic jam wasn’t too long, and I arrived near home safely. Actually, the uphill slope right in front of my house is quite steep, and fuel efficiency usually drops by 0.2 to 0.3 there, so I stopped measuring fuel consumption before that. The fuel stats were:

Average fuel consumption: 8.5L/100km (11.7 km/L)
Driving time: 2:39 hours
Distance: 185 km
Average speed: 72 km/h

Is ACC really better for fuel efficiency?

This was my first long-distance drive using ACC, and I was left with the strong impression that “when the car ahead disappears, it immediately tries to close the gap by accelerating hard.” When I drive myself, even if the car ahead disappears, I often think, “If I keep this pace, I’ll catch up to the car in front soon enough, so I’ll just cruise,” and don’t accelerate unnecessarily. But ACC accelerates and then brakes again when it detects a leading vehicle.

Despite that, the fuel efficiency wasn’t much different from when I drove myself, and considering there was some traffic on the way back, this fuel consumption suggests that ACC drives in a car-friendly way. Above all, it’s much easier when traffic is heavy.

That said, driving about 370 km and 5 hours round-trip while constantly worrying about fuel efficiency wasn’t very enjoyable, so I realized again that when I’m in the Panamera, I’d rather just enjoy driving without overthinking it.