2010 Sonata...cruise doesn't work on hills....downshifts and rpms jump...no way to get good mileage on highway....have to keep shutting the cruise off as i approach hills..........Dealer says this is normal! Been driving cruise cars for 30 years..never had this problem before...saw other complaints about this online.
Please help!... Thanks. Tom

 

Hi Tom;

WhooHoo, my first post....

I noticed the same issue with my 2010 Sonata Limited and it's an annoying characteristic of the car. It's not really correct, however, to say the cruise control isn't working.

I discovered a "work around". When you are up to speed in 5th gear switch the gear selector over to the manual shift position and then set your cruise speed.

After doing this, the transmission will stay in 5th gear but the torque converter will automatically lock and unlock to help the car compensate for hills. It's much less dramatic than a full downshift and is what would happen if you were not using the cruise control and had the gear selector in the full automatic position (so long you don't mash the gas pedal).

I think it is prudent to use some common sense with this approach. When I drove over Mt. Hood recently there was a 18+ mile stretch of road that added 3000 ft. elevation. Much of the time I was using cruise control with the gear selector in the manual shift position but in 4th gear. My reason for this is that I wanted to avoid lugging the engine.

Give this method a try. I think you will like it.

None

 

Yep, totally normal. That's what happens when cars have engines with low torque and 4+gear transmissions.