I'd like to present a Road Vehicle GRF I've been working on since a couple of weeks: A set of off-road trucks, that fill in the gap between normal road vehicles and heavy hauling vehicles.
Outline
SUV (Supplement Unsurfaced Road Vehicle Set) supplies your OTTD game with a set of multipurpose off-road trucks (and SUVs ...), which can run on various Road Types. This makes the vehicles of this set the all-rounders you need on your strife to create a vast web of (bumpy) country roads.
Requirements
This set needs OpenTTD version 1.10 or above to work.
Other than that, it is recommended to use this set together with GRFs that provide unsurfaced Road Types.
Supported road type sets are:
- Country Roads
- Unspooled
- Docklands
- RATT Roads
- AuzRattRoads
- JF Ratt Roads
- U&RaTT
- Auge's Basic Roads
- Timberwolf's Roads
- Dutch ROad Project
- Polroad
- Road Hog
The trucks (and SUVs...) provided by this set include only vehicles made by namely manufactures of the more or less eastern parts of Germany, formerly German Democratic Republic, as well as former Czechoslovakia and former Soviet Union.
The vehicles (will) span, effectively, a time frame from the 1930s to the 2000s. However, as horse carts are (will be) included as well, this set can be used since the pre-industrial time (in future).
For most parts, the vehicles are realistic in power, capacity, 'life-span' etc.; however, some things can be configured via parameters to adapt to other, unrealistic, game styles, as well.
The featured types of vehicles are ...
Multifunctional Cars (a set of 'mufu's)

These tiny cars were designed to be used on industrial complexes, conveying small bits of cargoes around the site. However, since they are full-featured 4X4 cars, they can be used on unsurfaced tracks as well.
Supports all kinds of Road Types!
Can be easily refitted to every cargo available! (excluding long cargo like wood which would need some semi-trailer-fication, which was IRL available but not in this set, anyway, but hey, you've got your heavier hauling rigs...)
Cheap to buy, cheap to run, thus light in transportability!
SUVs ('normal' cars)

These cars are 'normal' Street runners, maybe even slightly adapted to unsurfaced roads. Though the later ones have full 4X4 ability and can run through the mud, as well. Typically separate passenger and express freight cars are being included. Purposed to run through small towns and villages spreading passengers, mail and goods. Later models (that's SUVs) can run on any unsurfaced road, as well, some models (that's without all wheel traction) only on surfaced roads.
Supports up to all kinds of Road Types!
Providing seats for about 3 passengers! (and a driver...)
Cheap and fast!
Tractors

Features small to heavy tractors that can be used from industrial sites to agriculture and forestry.
Can run on any surface, except Motorways! (for traffic reasons...)
Heaves up to three trailers filled with any of your precious cargoes!
Not cheap, yet slow!
Small Trucks (and buses...)

A vast set of small trucks that can even bring your passengers to the outermost areas of any map. Most come in separated truck and bus form type, the latter, however, limited in industrial usability.
Can run on any Road Type!
Heaves and hauls up to all kind of cargoes!
Not expensive, but efficient!
Big Trucks (or, rather big trucks...)

A variety of trucks designed to transport any sorts of industrial cargo. It even hauls oversized cargo on low-boy trailers, which non of the above types will be able to.
May run on any Road Type! (though yet has to been seen on motorways...)
Heaves and hauls all kinds of cargoes except PAX!
Supports a moderate amount of capacity!
Heavy howling vehicles (eh, hauling that is)

A set of dexter dogs, I mean, a set of tractor trucks, that may haul unreasonable heavy amounts of cargo, but only on heavy hauling tracks, the only one suited for them howling racks.
Only allowed to run on HAUL-able roads!
Expensive, but hauls heavy amounts of cargo!
Does not rime!
Special Features
Diverse Cargo Graphics for up to FIRS 3
Full 2X-Zoom Graphics
Vehicle Performance adapts to Road Surface
Vehicle Upgrades (if bought new)
Custom Sound Effects
Mail Compartment in some buses
Timeline of all vehicles Credits
Thanks are directed to andythenorth, supermop and McZapkie, whose GRFs (including their NML source...) inspired me a lot! Plus, a thanks to Richard Wheeler, whose Pixel Tool I excessively used creating the vehicle sprites, and George for some cargo graphics.

This set is licensed under GPLv2, unless parts of it are specified other.
Latest Release: Version 0.5.2
Jump to Release Posting
(Here you find a version for vanilla OpenTTD)
Changelog
V.0.1................all Multicars and 'SUVs', as well as early tractors included. A preview of tracked tractors included.
V.0.2................new cars, Unimogs, as well as all light trucks, vans and buses. Japanese translation included.
V.0.3................many new trucks, tractors and buses. Better smoke effects. Custom vehicle sounds.
V.0.4................new buses and a new light truck. Enhanced compatibility with supported Roadsets.
V.0.5................new light and heavy trucks. Mail compartment feature added.
Known Issues
1x zoom graphics might look not as good as their 2x zoom counterparts.
The alignment of vehicles and trailers might look wrong.
Buses with combined passenger/mail load cannot be automatically upgraded
Vehicles like the Unimog will generate an error message due to 0t load for certain cargoes (wood, pipes etc.) - the trailer can still load these cargoes, so please make sure to buy a trailer in the refit menu
What's next?
Big trucks! Heavy cargo! Tractor trucks? More buses!
Feedback wanted!
If you have any comment or feedback on this set, as well as wise remarks, or, finally, bug reports, please share your thoughts within this thread!

Yours, Krümelchen
*disclaimer: the author of this post is not responsible for external content ...