It is close to the smallest car I have converted, and by far the lowest, which was the big challenge in its case. But it is exactly the model and color of my my daily driver (at least on perfect-weather days like today), and I wanted to see "me" on the layout. The challenge was shortening the chassis more than the WBB chassis is meant to adjust: al ot of cutting metal and "re-machining" the chassis to adjust shorter. Then fitting the motor and its gearbox under the body was tough: I had to grind just a bit off the motor-gearbox case and a lot off the chassis, but I got it converted: the motor top is touching the back of the Ferrari body. Interestingly, the motor sits in the very middle of this car: it is indeed a mid-engined sports car!
Note in the photo above that I was able to fit the Ferrari model's model of the car's engine and its two red induction runners atop the lowered gearbox. I was particularly pleased with that.
The VW bus is the hardest conversion I have don. . It has a 2 mm shorter wheelbase so the chassis was even more of a challenge to shorten but the real problem was width: it is 3 mm narrower than the Ferrari model, and the narrowest vehcile I have converted. the
outside of the VW's body over the rear wheels is the exactly same width as the rear axle of a WBB sedan chassis is from outer edge of one wheel to outer edge of the opposite wheel. I have to cut the wheel well openings away to clear them: I've never actually seen a VW bus like that but it looks okay.
The Ferrari is not a good runner - not bad, but not great. It is a bit too light to keep its wheels and rollers firmly planted, and tends to run smoothly only at highway speeds or faster. That and its era mean I really don't have it on the layout much. By contrast the VW is nearly always on the layout. I put the boxlike interior volume to good use holding extra lead weight to hold it down firmly, and super-capacitors to give it ride through at low voltage, so it runs very slowly (scale 10 mph) if I want, and with its wheelbase (the shortest of any 'streets vehcile I have) it glides through curves hardly noticing them.