1999 Pontiac Sunfire. It was designed around the 2200 4 cyl. Literally. There was less than a hand width in between the serpentine belt and the passenger side fender. In order to pull the serpentine belt (which is necessary to do just about any repairs on the motor), you have to pull the belt, but first you mist take off the passenger side motor mount. Most serpentine belt tensioners can be access with a standard 1/2" ratchet. Not this one. A special tool must be purchased which is basically a flat bar with a 1/2" socket connector welded to it. Oh, and the oil filter is located DIRECTLY above the exhaust pipe. Impossible to change oil without some spilling onto the exhaust right neat the catalytic converter. Finally tried placing a sheet of tin foil over the exhaust first to help out, but it still makes a HUGE mess.
My favorite to work on was my Jeep Wrangler after I had built it. It was lifted SOA so I could crawl under it easily to reach stuff like oil filters, etc. I had a TPI 305 under the hood and was easy to get to the front of the motor and the spark plugs. The axles were International Scout II, so it was easy to find parts cheap. Biggest problem I had was remembering what part came from what vehicle, and the parts store guy thought I owned a whole fleet, when I only had one Jeep.