Escape Hissing Sound and Fuel Consumption

I had a somewhat similar issue with my Escape, although it's not a hybrid. That hissing sound when accelerating definitely rings a bell. Have you checked the intake hose? It's a pretty common problem for them to develop leaks, especially around the clamps. A leak in the intake system will cause the engine to suck in unmetered air after the mass airflow sensor, leading to higher fuel consumption and the check engine light. If you can hear hissing, you might be able to pinpoint the location of the leak. Sometimes it’s just a cracked hose, or a loose clamp.

That's interesting! Thanks for the tip! I'm not too familiar with car parts, but where exactly is the intake hose located, and how would I check for leaks? Is it something I can do myself, or am I better off taking it to a professional? I'm not sure I know what a mass airflow sensor is.

Okay, so the intake hose runs from the air filter box to the throttle body. The throttle body is what regulates the amount of air going into the engine. The hose is usually black rubber or plastic. To check for leaks, with the engine running (but be careful of moving parts!), listen closely around the hose and its connections. You might be able to feel air escaping. Some people use a spray bottle with soapy water; if you spray it on the hose and there's a leak, you'll see bubbles forming. The mass airflow sensor measures the amount of air entering the engine so the computer knows how much fuel to inject. Honestly, if you're not comfortable working on cars, it's probably best to take it to a shop. They can do a smoke test to pinpoint any leaks. It will cost around 100€.

You are a lifesaver! I took your advice and brought my Escape to a trusted mechanic. Turns out, it was indeed a leaking intake hose, just as you suspected! The smoke test confirmed it immediately. New hose installed, check engine light is gone, and the hissing is history! Cost me 100€ including labour. Thanks again for your help; I really appreciate it!