Manual transmission question for gearheads

[Bedwyr]

I just got back from a "vacation" in which I helped a sibling buy a car inside of three days. We were working between either a manual or hybrid car and one of the vehicles was a 2019 VW Jetta. We could not get the car to move uphill from a stop.

The car:
- 147HP, 4 cylinder with a turbocharger.
- Electronic parking brakes with a button (no friction handle).
- Manual transmission.
- Hill Assist feature with a two second timeout (car rolls back two seconds after removing the foot from the brake).

The driving situation:
- Second test drive with a really good experience on flat ground.
- Both the sibling and I are very comfortable manual drivers and used to working with hills, being from Seattle (personally I love doing it when there).
- The sales rep was not a manual driver and was in the backseat.
- On a steep residential hill, the sibling could not get the car moving over the next ten minutes no matter what configuration of control inputs were used, trying out that parking button, etc. We got to the point of using the hazard lights and waving other cars around.
- After getting to the top of the hill, I took over and we drove back down to a gentler side street. I'm more comfortable with hill starts and could only get the car moving on one out of every four attempts, varying clutch/throttle management. And when I did, the vehicle would just not deliver power. I'd be nursing the vehicle forward on the ragged edge of stalling at 400-500rpm.

After about a half hour of this we had to call time-of-death on the sale. We were really broke up about it as the value/power/features and driving experience on flat surfaces were by far the best combination. We drove a manual Kia that afternoon with no problems (I recall this one had a regular parking brake and no timeout on the hill assist feature, also no power delivery problems from stop).

Any ideas why this experience would be so stark? I have a couple of theories, but I'm a prop-head, not a gear-head. Airplane engines are far simpler. One guess is the ECU was restricting the power delivery till some forward speed. Another is that the turbocharger wasn't powered enough from idle to add needed power to the struggling 4 cylinder engine.

[MarauderD]

As a former car sales guy, the tech is progressing quickly, but here is my .02$.

Turbo chargers need time and RPM to spin up, so it isn't at play when moving from a dead stop.  Unless you are trying to peel out, which isn't at play here.

147 HP is plenty for steep hills.  I have done Divisidero in San Francisco in a manual tranmission, and that makes Queen Anne in Seattle look like Nebraska.

Hill Assists are actually pretty simple devices, so unless VW totally botched there, it really shouldn't effect this situation at all.

Electronic parking breaks can be a bit tetchy in my experience.  Was this in play when your sibling was starting on the steep hill?

Curious as to what was going on here,

Mad

[Bedwyr]

We thought it might and played with having it engaged and disengaged from stop. No change in result. Basically, I couldn't use clutch/throttle interactions to reliably deliver power to the wheels. I tried things like throttle high-feathering-to-low, low-to-high, low-to-mid, engaging throttle earlier and later vs. disengaging the clutch. Nothing. The (non manual driver) sales person was honestly flummoxed.

The key bit for us was that two other cars performed perfectly well. It's possible it was the assist timing out, but I don't think so. The engine interaction was just... troubling.


Functionally it doesn't matter. The sibling unit has to be comfortable with the car, period. So it was probably going to be a no-sale by the time I took the controls. But it is a curious thing.

[Daryk]

The fact that the sales rep was "flummoxed" was really all you needed to know.  If they couldn't explain what was going on, they're not someone to buy anything from.

[Feenix74]

I believe it may be a problem with the Hill Start Assist in that vehicle. There have been reports on the VW forums of some of the new VWs with the Hill Start Assist and the electronic push button park brake (aka "emergency brake" as you Americans like to call it) having issues where the Hill Start Assist refuses to release the brakes and you end up stalling the vehicle trying to do a hill start.

While I am a 22 year VW-fanatic, my current ride is a manual 2011 VW Caddy (VW peoplemover van which I don't think is available in the US) which has Hill Hold Assist and a manual style park/hand brake, so unfortunately I cannot give you personal experience and a solution only what I have seen reported by others. You might want to do some googling.

[Bedwyr]

I believe it may be a problem with the Hill Start Assist in that vehicle. There have been reports on the VW forums of some of the new VWs with the Hill Start Assist and the electronic push button park brake (aka "emergency brake" as you Americans like to call it) having issues where the Hill Start Assist refuses to release the brakes and you end up stalling the vehicle trying to do a hill start.

Very very interesting possibility. Yeah, I'd insert that as a candidate. There's no way it was the respective skill (lack thereof) of either of us.