Apart from my two long outstation trips last year, to the extreme South and North of India, and to a number of ATMs, I also did many local day and overnight trips to places around Mumbai, mostly during and after the monsoon.
Though some of these were solo or group trips involving public transport like user-friendly S.T buses, the majority were with travel buddies, pooling our bikes and cars to get to where we were going, which many a time left us pitting our wits against over-friendly S.T bus drivers.
The car & bike trips I did in 2009 were:
Khandala - 1 car - 5 people
Vikramgad - 1 car - 4 people
Lohagad - 1 car - 5 people
Pavana Lake - 1 car - 5 people
Shivneri - 2 bikes - 4 people
Kashid - 1 car - 4 people
Korlai - 3 bikes - 5 people
Diveagar - 2 cars - 5 people
Yeoor Hills - 3 bikes - 6 people
So that was 6 car trips and 3 bike trips in 2009, all to beautiful locales (or wet and cut-off, depending on your point of view) a few hours (or many long boring hours, depending on your point of view) drive or ride from the city. It was at this time that I noticed how different bike and car travel can be. I've noted the differences below, using whatever categories I could quickly rustle up in my mind in order to give this post some semblance of intelligent thought mixed with quality writing drawing on extensive travel experience.
Capacity
One bike carries 1 or 2 people, while a car can carry 1 to 5, or more. The consequences of this mind-blasting fact (not mind-blowing, mind you) follow below.
Productivity
A bike trip involves at least 100%-50% of your group spending their time riding (note the clever but unnecessary use of percentages). Even pillion riders have little to do apart from pretending that their weight acts as a counter balance that helps the rider control his/her bike at curves, and trying not to fall off.
Driving a car, on the only other available hand, involves 100%-20% (and even less in higher passenger capacity vehicles) of your group driving, at any one point of time. This frees up a lot of time for the rest of the group, giving them a (usually wasted) chance to be more productive.
Driver/Rider recycle rate
If you have two people to a bike, and both take turns riding, your rider to vehicle ratio is going to be 2:1, assuming both have licenses, and I don't mean the two licenses at the front and back of the bike.
A car just needs one driver (surprise!), so with a group of 4 or 5 taking turns to drive, the driver to vehicle ratio is going to be 4:1 or 5:1 respectively (or more in higher passenger capacity vehicles), meaning the group gets to conserve more of their (usually wasted) energy, which leads to the next point.
Driving exhaustion
Bikes leave you relatively more tired than cars. It doesn't matter if you're riding alone or with a pillion rider. Driving a car is less exhausting than riding a bike.
Even with a pillion rider, a bike doesn't allow for a lot of chit chat while travelling, especially with helmets on. Unless you make use of some body/head tapping sign language, you're forced to talk to each other only during breaks or when you reach your destination.
No such problem in a car, in which you even have the freedom to read each other's tweets. Cars enable you to depend on your group to keep you occupied, especially if the scenery is monotonous and you're more socially inclined.
Storage
A rider & a pillion can both carry medium sized (around 30 litre) backpacks, though this would be somewhat uncomfortable for the bike rider as he/she might have to carry his/her baggage around the front rather than at the back, when carrying a pillion. This lack of baggage space discourages longer biking trips with a pillion, for want of comfort, forcing you to ride solo. And solo or not, you'd have to arrange to keep your bags dry during rainy trips.
In a car, there's room for more baggage, especially the heavier kind, like bottles of alcohol, iceboxes, tripods, U.F.O detection apparatus, etc. Furthermore, this cargo can be stored in a dry space specifically meant for it, and not on your back out in the open.
Speed and Time
On a good wide straight road, cars are generally quicker, safely travelling at over 100 km/hr, though on most other roads, both are more or less the same, travelling at speeds varying between 60 and 80 km/hr.
During rainy trips, cars would make better time, as bikes would be forced to slow down or stop completely if the rider has a case of hydrophobia.
Expense
Bikes are cheaper to run - their mileage is twice that of cars.
Experience
No car trip compares to the feel of a bike ride. The freedom, the world passing you by, the (natural A.C) breeze. A car window is no comparison.
Conclusion
Cars have the upper hand when it comes to most of the factors above. They're better in terms of comfort & luggage space; for trips involving rain & monotonous scenery; and if you don't like extended bouts of solitude.
Bike travel is better for travelling light and saving money; for exploratory trips involving lots of quick stops, detours & U-turns; and when you want the entire journey to be an incredible travel experience like no other and not just a means to an end.
