I did delhi bangalore over this sat & sun (i.e. 18th and 19th April 2009), the road conditions, from bombay-pune expressway flyover where the old bombay-pune road and expressway deviates is as follows:
a. To pune on the bombay pune expressway - ok to good - while you can do great speeds on this stretch, the road surface is not the best.. There are some portions around khandala/lonavala where you need to slow down quite a bit - this does affect the average a bit, but otherwise it is still one of the better roads out there..
b. Pune bypass - essentially from end of expressway to the first toll booth on the way to satara - good road surface, but we did find quite a bit of city traffic on a sunday afternoon, I do not know how good/bad it would be on other days..
c. Pune to satara after first toll booth - the road surface is great and there was some light to heavy traffic - the kambakakta ghat (i do not know the exact spelling) was pretty crowded, but otherwise this stretch is pretty good
d. Satara - kohlapur - We did find some traffic, but not as much as it was till satara - good road surface but speeds > 140km/h not recommended on most cars on this stretch because of traffic conditions..
e. Kohlapur to Belgaum to Hubli/Dharwad bypass - Excellent roads and very mild traffic - we did speeds of upto 180km/h and averaged around 100km per hour on this stretch. In many parts of this road, you can see a few kilometers ahead of you.. Curves can be taken at pretty high speeds if you and your car can handle the speeds safely.. Also, while this road is essentially a 4 lane road, there are many 6 laned sections. All bridges and ghat sections are 6 laned. Just be careful about driving at high speeds as this section is not fenced unlike expressways, so there can be stray cattle, pets and humans..
f. Hubli/Dharwad bypass - this is a 2 lane single carriageway with quite a bit of traffic - speeds can remain restricted depending on the traffic
g. Post Hubli for around 50km (i did not note down the distance) - Great highway, light traffic on a sunday evening and we were restricted in terms of speed due to it being night time but I suppose one can safely do very high speeds.. Great road surface..
h. Around 50kms after Hubli to a few kms after chitradurga - road construction stopped, so bad roads, no lane markers, lots of diversions - we did not find much traffic on a sunday evening after around 8pm. Also there are 2 railway crossings, we got stuck in one :-( There are quite a few long 4 laned stretches, but there are way too many diversions on this stretch, so be careful.. Some big potholes were also there..
i. A few kms after chitradurga to around begining of tumkur - Excellent roads - I did see fencing around the roads and even at night time, we did great speeds.. We were limited a bit due to wet roads post rains on this stretch, but in day time v. high speeds should be possible during the day time.. Quite a few sections on this road are also 6 laned, but still it is mostly 4 laned..
j. Tumkur town - Road under construction, and I suppose pretty clogged up with traffic during the day - We passed tumkur at around 1am and did not find much traffic, but were limited in terms of speeds due to spead breakers and frequent diversons..
h. Tumkur to around bangalore - Decent 4 laned road, but not as good as the other roads..
i. After some point near bangalore to bangalore city - road surface is not so bad, but due to metro construction the road is pretty bad - if possible, use NICE road to get to tumkur road from within bangalore city.. I had to go to around yashwantpur, so I could not use the NICE road..