Basically, yes.

A 2.4 Camry is close in terms of economy to a 2.0... around 6-7 km/l in traffic.

The 3.5 is between 4-6 km/l... better than an Expedition naman (around 3-4).

1-2 km/l means little... on the highway.

In the city, a 1-2 km/l difference is 20-40% more gas. Prepare to spend a lot more per trip.

There's a reason why, secondhand, the prices of the 2.4 and 3.5 are very close, even if the 3.5 was hundreds of thousands more when they were new.