If wanting to do both onroad and race a Tamiya there are three main routes.
Cheapest / Beginner : Tamiya TT02-S. The cheapest way to get a chassis that will get around the local track. It is not going to destroy the top level cars but with a few choice hop-ups it is able to be a good introduction into the class. It is easy to build, adjustable and easy to drive. I have hopped one and also designed a few special parts for it (Roll bar mounts, and a top deck). I even raced it in the national and scored a place in the B-Final. The amount I spent on it to go that far is way past what you would normally spend, although there is also something to be said about the concept of just investing in small chunks as your ability gets better. (Top upgrades - Alloy Prop, High speed gear set and yeah racing adjustable motor mount (Povides you with the ability to change the gearing to match the low FDR you need for high turn motors etc), Front universals, Front diff locker (Spools are great). Centre carbon deck etc.
Intermediate / Beginner : Tamiya TA07pro. This kit is a great price and not much more than the TT02-S (I am not referring to the TA07 R or TA07MS here). This car is very good as it comes with some great hop-ups and importantly shares a lot of the DNA of the TRF419 and TRF419X. The kit chassis is good to go at the local club, although I would suggest buying the roll bar set once you get the car around the track as it will allow you to tune the suspension more. The kit chassis is quite flexible which is ok on most tracks as it makes the car easy to race, although if running in America you will want to get some of the carbon stiffeners, or the carbon tub to help stiffen the car up. In the uk I have added these just to try it, but it is too stiff for indoor carpet in my opinion.
Intermediate / Pro : TRF419XR or TA07MS these are both top end touring cars designed by the Tamiya Racing Factory. They are both very good, the XR is the best TC I have ever raced, its quick and consistent. It has everything you need to win the A-Final in the box other than the most important thing which is actual skill. In reality all of the top end cars can win, but it is down to other aspects such as set-up, driving skill, tyre prep etc. The TA07Ms is also up there, and the motor adjustment means it could well be better at some tracks than other Top end chassis as it will have a more refined weight bias.
I enjoy racing my Tamiya's
Here are some links
TA07ms and TA07 reviews will be on www.TheRCRacer.com soon, along with a big guide on tuning the TT02-S