That $35k in trade would be like $38.5k selling outright considering the tax advantage of trading here in KS. Sales tax is damn near 10% nowadays, and you pay sales tax on the difference ~10% x (new-trade). Pretty much the ONLY benefit of trading here, besides convenience vs. selling outright.
That said, $35k's a damn near spectacular offer IMO. Dealer must have a buyer already and plans to flip it fast. Market is $40 to 43 brand new. Probably $35k for a stripper 1SS (non 1LE).
FWIW, we got $26k trade (~$28.6k outright) for our '15 1LE back in December (was 14 mo old and had just over 10k miles). Paid around $39k new. Needed tires and those you can figure at ~$1.5k, so like $30k net net on that trade ($10k delta in 12 mo). Pay to play...around $1/mile.
Use GM Card rebate and get your best possible deal new to soften the blow....