I wanted to add my own thoughts to this board. I think as some have said, it would be nice to have more flexibility to paint and customize.
For example, being able to paint body parts separately (ie… Doors, fender, etc…) as well as cars having more body paint groups. The Apollo IE has a "interesting: two tone split which is okay, but I don’t understand why the car did not receive additional paint groups for the different sections.
I also would like to be able to add window decals.
Anther addition is be able to change the number of transmission gears. Other transmissions are available with engine upgrades, however, I personally like to sometimes keep the original engine like the Shelby daytona, but would like to add a 5th gear.
I think another step would be to add fender flares to all vehicles. Widebody panels would be nice, but my thought is similar to the front splitter and spoiler that are available on every vehicle, the fender flares would allow additional wheel widths. As well as more inclusion of aftermarket suppliers for body kits, accessories, etc. I love the ability to customize to make the cars personal and I there are many companies that would suit the cars.
Another update I would like to see in Horizon is support for offroading. The ability to add larger tires like 35, 37, 40s and additional lifts 2", 4", etc… There are a great number of offroaders and I feel that adding more support for crawling and climbing would be great, not just high speed offroading. As well as off road sections designed for such.
As far as the houses, I love that we can have multiple locations. I would like to see in Horizon 5 an ability to have a garage where we can walk through and see our cars. Possibly range the size of the garage by the type of house (2 car, 4 car, 10 car, 20 car). I would love to showoff my cars to friends or online players without having to call in a new car one by one.
Here is my desire for additional cars:
2021 Alfa Romeo Gulia GTA
2017 Dodge Challenger RT Scat Pack
2013 Dodge Dart
Callaway C4
Callaway C7
Callaway C12
2020 Chrysler Pacifica (customization from van culture and ability to add a hellcat engine
)
2004 Chrysler ME412
2004 Chrysler PT Cruiser GT
2005 Chrysler Crossfire SRT6
Factory Five GTM
Factory Five 818
Factory Five F9
Henessey F5
Gordon Murray T50 and T50s
Gumpert Apollo
2020 Jeep Gladiator (ability to choose tire sizes like 35 or 37 as well as removable roof and doors as mentioned in other posts)
2020 Jeep Wrangler 4 door
Mayback Exelero
1997 Mclaren F1 LM or LM Aero parts available for the F1 (Front bumper, hood, side skirts, spoiler, rear bumper)
2000 Plymouth Prowler
Revero GT/GTS
Rinspeed cars (There are many interesting concepts like the roadster and rocket)
Tesla roadster
Tesla 3
Tesla X
Tesla S
Tesla Y
Tesla Semi
Tesla Cybertruck
Lastly, a possible next step for Forza Horizon or across Forza in general, is the ability to build our own cars. Select an engine, transmission, gearing, specific chassis like front engine/mid engine, rear engine. The game already allows a lot of finetuning, but I think the next progression could be the ability to build a specific setup outside of using current cars. Possibly select a new chassis and body. Even make it a side series where we have various challenges were we compete against the best cars to see if our custom car can beat others in high speed, drift, offroad baja, offroad climbing/crawling, rally, etc. One feature I have seen that I really enjoyed was the body morphing studio seen on Supercar Street Challenge. I loved being able to create my own car body and features and I feel that would be a great thing in Forza Horizon since we already get the opportunity to tune the car to a high degree.
Horizon has done a great job with including a lot of cars and celebrating many great cars throughout history. I wish that the previous car list we have seen in older games was carried over.