Google maps is a great way to layout a road network and obviously an adventuring party that owns a roadster(s) benefits from numerous paved roads. If you also want to a high speed chase or car combat against Mad Ranegan, you need at least a few multi lane highways. Modern highways often bypass one lane towns and watering holes, and have bridges, tunnels, and engineered grading for ease and speed. The more highways the more numerous road vehicles become displacing the horse, train, and ferry networks in your campaign.
Personally, I tend to emphasize the grit and grime of my steampunk campaigns, hence the ubiquitous googles and breathing masks.
In my games, I often make a journey the first challenge and maximize skill use. So rather than a road map I usually handle it on the fly. Even within my cities not every street is paved and outside very few pounded dirt roads have more than a seasonal coat of tar or oil to cut down on summer dust.
Here are some road encounter ideas incorporating Knowledge checks... Arcana
Gom Shao uses giant snails to create glassy pavement and elevated roads with hardened mucous. Enchantments may be applied to create artificial gravity (double sided bridges, vertical roads, tubular highways), earthquake proofing, spontaneous road blocks/tire shredders, heated roads, levitation, advertising illusions, treadmill roads, glowing signs/traffic markings, fog barriers, etc (Go Nuts). Magical vehicle identification and traffic rules would also be included. Dungeoneering
The zaruto and rageiac built a few secret underground roads. Most have now partially collapsed or fallen into disrepair and some are used as illicit race tracks or smuggler routes. You might also be blasting or tunneling a new road or railway through the mountains; or you can identify that coal seam in that abandoned mine you spotted earlier. Engineering
Fellow travelers might be scarce and you need to perform your own repairs or servicing. Also good for identifying other makes and models of roadsters and its top speed, acceleration, engine type, modifications, hit point condition, etc. Geography
Weather is a major obstacle and must be planned for in advance (overheating, dust storms, no snow plows, landslides, flooding, and tire binding mud). Signage is rare and can be misleading to favor a commercial interest, bandit ambush, or just wrong. Towns along the way may or may not have the resources you need or a friendly populous so you need to know if you should make a detour or not.History
Often roads are built on old trails and game trails. Famous or infamous events on this road may be useful in social interaction or discovery.Local
Service roads are often a convoluted web between sites that are rarely the most direct as they were built mostly by loggers and farmers for commercial use. Regional roads may have traditions, laws, hazards, and detours known to localsNature
Predicting a storm is always useful for a traveler and recognizing a section of road as an animal crossing can avoid an expensive collision. You might also be able to find that special sap you can use to seal a punctured tire or that water hole to refill your engine. Nobility
Some roads or bridges are private or built and maintained by a regional noble or 'baron of industry' and demand a toll. This skill can be used to map, find an exemption, or expose a con artist on a toll road. Planes
It is said the road to hell is paved by good intentions and the highway to heaven is narrow. Supernatural events such as plane shifts, time jumps, and time loops can occur on isolated roads or engineered into vehicles. Experimental dimensional tunnels also exist to move through a solid object such as a building or mountain. This skill can be used to identify such a phenomenon or device. Religion
It is said that some lonely roads are haunted and a hitchhiker, train crossing or tailgater can be far more dangerous than they first appear. Mazan and Rausch often have religious iconography on their vehicles.