In 1977, I bought a new Toyota FJ-40 Landcruiser which was built like a tank. But the gas mileage sucked so I had the smog-equipment removed and installed headers and a 4-barrel carburetor. This only marginally improved the power and the mileage.
In 1983, I bought a new Jeep CJ-7. Because I had to make the FJ-40 California smog-legal, I found a shop that "claimed" that they could locate and install the smog equipment. Two years later, the shop "gave up".
Since my FJ-40 had been sitting in the shop's back-lot (subjected to the weather and vandalism), I ended up selling the FJ-40 for $500 salvage).
I kept the CJ-7 for 18 YEARS and made NO modifications to it. I drove it 99 44/100% of the time back-and-forth to work and 56/100% off-roading (in Death Valley, Canyonlands, Glamis and other places). It was an OK vehicle but it had a lot of problems with the Pulse-Air smog system and with the transmission.
In 2004, I sold the CJ-7 for $7,000 (!) and bought the Jeep Liberty. I've made NO modifications to it. Except for regular maintenance (fluid and filter changes and one tune-up, etc), it's been a good vehicle. It it hasn't been off-road except for maybe 5 miles.